Method for varying the transport properties of a film cast from a sulfonated copolymer

ABSTRACT

A method for varying the transport properties of a film cast from a polymer having at least two polymer end blocks A and at least one polymer interior block B wherein each A block is a polymer block resistant to sulfonation and each B block is a polymer block susceptible to sulfonation, and wherein said A and B blocks do not contain any significant levels of olefinic unsaturation. The method includes casting the polymer using a solvent mixture having two or more solvents selected from the group consisting of polar solvents and non-polar solvents.

CROSS-REFERENCE RELATED APPLICATIONS

This application is a divisional application of U.S. Ser. No. 12/763,979filed Apr. 20, 2010, the entire contents of which is hereby incorporatedby reference in its entirety, said application Ser. No. 12/763,979 beinga continuation application of U.S. application Ser. No. 11/458,856 filedJul. 20, 2006, the entire contents of which is hereby incorporated byreference, said U.S. application Ser. No. 11/458,856 claims priority toU.S. Provisional Application 60/701,768, the entire contents of which ishereby incorporated by reference.

FIELD OF THE INVENTION

The present disclosure relates to sulfonated block copolymers and to themethods for making such block copolymers. In particular the presentdisclosure is directed to a method for varying the transport propertiesof a film cast from a polymer having at least two polymer end blocks Aand at least one polymer interior block B wherein each A block is apolymer block resistant to sulfonation and each B block is a polymerblock susceptible to sulfonation, and wherein said A and B blocks do notcontain any significant levels of olefinic unsaturation. The methodincludes casting the polymer using a solvent mixture having two or moresolvents selected from the group consisting of polar solvents andnon-polar solvents.

BACKGROUND OF THE INVENTION

The preparation of styrene diene block copolymers (“SBC”) is well known.In a representative synthetic method, an initiator compound is used tostart the polymerization of one monomer. The reaction is allowed toproceed until all of the monomer is consumed, resulting in a livinghomopolymer. To this living homopolymer is added a second monomer thatis chemically different from the first. The living end of the firstpolymer serves as the site for continued polymerization, therebyincorporating the second monomer as a distinct block into the linearpolymer. The block copolymer so grown is living until terminated.Termination converts the living end of the block copolymer into anon-propagating species, thereby rendering the polymer non-reactivetowards a monomer or coupling agent. A polymer so terminated is commonlyreferred to as a diblock copolymer. If the polymer is not terminated theliving block copolymers can be reacted with additional monomer to form asequential linear block copolymer. Alternatively, the living blockcopolymer can be contacted with multifunctional agents commonly referredto as coupling agents. Coupling two of the living ends together resultsin a linear triblock copolymer having twice the molecular weight of thestarting, living, diblock copolymer. Coupling more than two of theliving ends together results in a radial block copolymer architecturehaving at least three arms.

One of the first patents on linear ABA block copolymers made withstyrene and butadiene is U.S. Pat. No. 3,149,182. These polymers in turncould be hydrogenated to form more stable block copolymers, such asthose described in U.S. Pat. Nos. 3,595,942 and Re. 27,145. Selectivehydrogenation to remove the C═C moieties in the polydiene segment ofsuch polymers is critical in preparing block copolymers with goodthermal and chemical resistance, particularly resistance to oxidativedegradation.

Through the years, there have been many modifications made to such blockcopolymers to change and improve properties. One such modification hasbeen to sulfonate the block copolymer. One of the first such sulfonatedblock copolymers is disclosed, for example, in U.S. Pat. No. 3,577,357to Winkler. The resulting block copolymer was characterized as havingthe general configuration A-B-(B-A)1-5, wherein each A is anon-elastomeric sulfonated monovinyl arene polymer block and each B is asubstantially saturated elastomeric alpha-olefin polymer block, saidblock copolymer being sulfonated to an extent sufficient to provide atleast 1% by weight of sulfur in the total polymer and up to onesulfonated constituent for each monovinyl arene unit. The sulfonatedpolymers could be used as such, or could be used in the form of theiracid, alkali metal salt, ammonium salt or amine salt. In the Winklerpatent, a polystyrene-hydrogenated polyisoprene-polystyrene triblockcopolymer was treated with a sulfonating agent comprising sulfurtrioxide/triethyl phosphate in 1,2-dichloroethane. Such block copolymersexhibited water absorption characteristics that might be useful in waterpurification membranes and the like.

The sulfonation of unsaturated styrene-diene block copolymers isdisclosed in O'Neill et al, U.S. Pat. No. 3,642,953.Polystyrene-polyisoprene-polystyrene was sulfonated usingchloro-sulfonic acid in diethyl ether. Since the sulfonic acidfunctionality incorporated into the polymer promotes oxidation and theresidual C═C sites left in the polymer backbone are prone to oxidation,these polymers had limited utility. As stated in column 3, line 38, ofthis patent: “The unsaturated block copolymer sulfonic acids obtained bythis process are subject to rapid oxidative degradation in air,therefore, they must be handled under anaerobic conditions and/orstabilized with anti-oxidants until they have been cast from solutioninto their final form and converted to the more stable salt byneutralization or ion-exchange.” The sulfonated, unsaturated blockpolymers prepared in the experiments outlined in the Examples of theO'Neill et al patent were cast as produced into thin films. The filmsexhibited excessive swelling (up to 1600% wt water uptake) and wereweak. While the cast films could be stabilized by treatment with anexcess of base and their properties did improve somewhat onneutralization (still only 300 to 500 psi of tensile strength); thefilms in the sulfonate salt form were now insoluble and could not bereshaped. Similarly, Makowski et al, U.S. Pat. No. 3,870,841 includesexamples of sulfonation of a t-butylstyrene/isoprene random copolymer.As these sulfonated polymers have C═C sites in their backbone, they arenot expected to be oxidatively stable in the sulfonic acid form either.Such polymers were used for applications requiring limited flexibility,and are not expected to have acceptable overall physical properties.Another sulfonated styrene/butadiene copolymer is disclosed in U.S. Pat.No. 6,110,616, Sheikh-Ali et al, where an SBR-type random copolymer issulfonated.

Another route to make sulfonated block copolymers is disclosed in Bataset al, U.S. Pat. No. 5,239,010, where an acyl sulfate is reacted with aselectively hydrogenated block copolymer composed of at least oneconjugated diene block and one alkenyl arene block. After hydrogenation,the block copolymer is modified by attaching sulfonic acid functionalgroups primarily in the alkenyl arene blocks (A blocks). The mechanicalproperties may be varied and controlled by varying the degree offunctionalization (amount of sulfonation) and the degree ofneutralization of the sulfonic acid groups to metal sulfonated salts.

In Pottick et al, U.S. Pat. No. 5,516,831, a blend of an aliphatichydrocarbon oil and a functionalized, selectively hydrogenated blockcopolymer to which has been grafted sulfonic functional groups isdisclosed. In the block copolymer of Pottick et al, substantially all ofthe sulfonic functional groups are grafted to the block copolymer on thealkenyl arene polymer block A, as opposed to the substantiallycompletely, hydrogenated conjugated diene block copolymer B.Neutralization of the acid groups to a metal salt was preferred toprepare oil extended blends that retained substantial amounts ofnon-extended mechanical properties.

The block copolymer blends were used for adhesives and sealants, asmodifiers for lubricants, fuels and the like.

Recently there has been more attention given to the use of sulfonatedblock copolymers for fuel cells. For example, Ehrenberg et al, U.S. Pat.No. 5,468,574, discloses the use of a membrane comprising a graftcopolymer of sulfonated styrene and butadiene. In the examples, an SEBSblock copolymer (i.e., a selectively hydrogenatedstyrene/butadiene/styrene triblock copolymer) was sulfonated with sulfurtrioxide to an extent of at least 25 mol percent basis the number ofstyrene units in the block copolymer. As shown in the patent, thesulfonic acid groups are all attached to the styrene units. Thedeleterious effects of water induced swelling in such membranes arediscussed in the article by J. Won et al, titled “Fixation of NanosizedProton Transport Channels in Membranes”, Macromolecules, 2003, 36,3228-3234 (Apr. 8, 2003). As disclosed in the Macromolecules article, amembrane was prepared by solvent casting a sample (from Aldrich) of asulfonated (45 mol % basis styrene content) SEBS (Mw about 80,000, 28% wstyrene) polymer onto glass. The membrane was immersed in water andfound to absorb over 70% of its dry weight in water as a consequence ofswelling. The rate of methanol transport through the water-swollenmembrane was then tested and found to be undesirably high. This is not apreferred result for direct methanol fuel cell (DMFC) applications wheresegregation of methanol to only one compartment of the cell is essentialfor the device to generate electrical power. For these applications,“methanol crossover needs to be reduced, while maintaining protonconductivity and mechanical strength, to improve fuel cell performance.”This problem was overcome to a certain extent, as described in thereport by J. Won et. al, by first casting a film of a styrene-dieneblock copolymer, radiation crosslinking the film (cSBS), and thensulfonating the pre-formed article. While crosslinking the blockcopolymer prior to sulfonation overcame the problem of excessiveswelling that was observed when an S-E/B-S polymer that was selectivelysulfonated in the outer blocks was used to form a membrane, crosslinkingtechnology is limited in its utility to thin, transparent articles thatare readily penetrated by the radiation source. In addition, sulfonationof the crosslinked article is time consuming and uses an excess ofdichloroethane (DCE). As reported by J. Won et. al, “The cSBS film wasswollen in an excess amount of DCE overnight. The solution was heated to50° C. and purged with nitrogen for 30 min. Then the acetyl sulfatesolution (produced with the procedure described above) was added.” “Thesolution was stirred for 4 h at this temperature, and then the reactionwas terminated by the addition of 2-propanol, resulting in a sulfonatedSBS cross-linked membrane (scSBS).” Cleaning up the sulfonated articlewas also problematic. “The membrane was washed in boiling water and manytimes with cold water. The complete removal of residual acid from thefinal product after sulfonation is important since it can interfere withthe properties of the final product.”

Still another type of block copolymer that has been sulfonated in thepast is selectively hydrogenated styrene/butadiene block copolymers thathave a controlled distribution interior block containing both styreneand butadiene, as opposed to the normal block copolymers that justcontain butadiene in the interior block. Such block copolymers aredisclosed in Published U.S. Patent Application Nos. 2003/0176582 and2005/0137349, as well as PCT Published Application WO 2005/03812.

In the sulfonated block copolymers disclosed above, invariably the outer(hard) blocks are sulfonated due to the presence of styrene in the outerblocks. This means that upon exposure to water, hydration of the harddomains in the material will result in plasticization of those domainsand significant softening. This softening of the hard domains results ina marked decrease in the mechanical integrity of membranes prepared fromthese block copolymers. Thus, there is a risk that when exposed to waterany structure supported by these prior art sulfonated block copolymerswill not have sufficient strength to maintain its shape. Hence, thereare limits to how to use such a block copolymer and limits on its enduse applications.

Other prior art sulfonated polymers are taught where the end blocks andinterior blocks do not include hydrogenated dienes. U.S. Pat. No.4,505,827 to Rose et al relates to a “water-dispersible” BAB triblockcopolymer wherein the B blocks are hydrophobic blocks such as alkyl orsulfonated poly(t-butyl styrene) and the A blocks are hydrophilic blockssuch as sulfonated poly(vinyl toluene). A key aspect of the polymersdisclosed in Rose et al is that they must be “water dispersible”, sincethe uses contemplated for the polymer are for drilling muds or forviscosity modification. Rose et al states at column 3, lines 51 to 52that the polymer “exhibits hydrophobe association capabilities whendispersed in an aqueous medium.” Rose et al. goes on to state in lines53 to 56 that “[F]or purposes of the invention, such a polymer is onewhich, when mixed with water, the resulting mixture is transparent ortranslucent, and not milky white as in the case of a dispersion of awater-insoluble polymer.”

The polymer of Rose et al. is water-dispersible since the t-butylstyrene blocks are not large—typically the block copolymer will haveless than 20 mole percent of B blocks, preferably from about 0.1 toabout 2 mol percent. In addition, the B end blocks will likely contain asignificant amount of sulfonation.

U.S. Pat. No. 4,492,785 to Valint et al. relates to “water soluble blockpolymers” which are viscosification agents for water. Thesewater-soluble block copolymers are either diblock polymers of t-butylstyrene/metal styrene sulfonate or triblock polymers of t-butylstyrene/metal styrene sulfonate/t-butyl styrene. It appears from thestructures and properties given that the interior block styrene is 100%sulfonated. This will result in the polymer being water-soluble.Further, in the structures given, each of the end blocks will comprise0.25 to 7.5 mol percent of the polymer. With such a large interior blockthat is fully sulfonated, and has relatively small end blocks, thepolymers will invariably be water-soluble.

None of the prior art references noted above disclose sulfonatedpolymers based on styrene and/or t-butyl styrene that are in a solidstate in the presence of water and have both high water transportproperties and sufficient wet strength. Accordingly, what is needed is asemi-permeable membrane with high water transport properties thatmaintains sufficient wet strength for a wide variety of applications.

SUMMARY OF THE INVENTION

It has now surprisingly been discovered that it is possible to achievehigh water transport properties while maintaining sufficient wetstrength for a wide variety of applications by using sulfonated blockcopolymers having one or more internal blocks that are susceptible tosulfonation and outer blocks that are resistant to sulfonation. Thesesulfonated saturated block copolymers of the present invention exhibit abalance of properties, including water transport, wet strength,dimensional stability and processability that have heretofore beenunachievable. It has been discovered that when sulfonation is limited toone or more internal block(s) of the block copolymer, hydrophobicity ofthe outer blocks is retained, and hence their integrity in the presenceof a hydrated center or rubber phase. The means by which sulfonationwould be directed selectively to the internal or interior block is by,for example, the use of para substituted styrenic monomers such aspara-tert-butylstyrene in the outer blocks. The large alkyl substituentat the para-position on the styrene ring reduces the reactivity of thering towards sulfonation, thereby directing the sulfonation to one ormore of the internal or interior block(s) of the polymer.

A key feature of sulfonated block copolymers having sulfonationresistant end blocks is that they can be formed into solid objects orarticles which retain their solid character even in the presence of anexcess of water. A solid is recognized as a material that does not flowunder the stress of its own weight. The polymers of the presentinvention may be cast into solid membranes. While these membranesefficiently transport water vapor, they are solids even in the presenceof an excess of water. The solid character of these membranes in watermay be demonstrated by testing their resistance to flow under tensilestress while submerged in water. A simple tensile test, according to themethods outlined in ASTM D412, may be performed on the membrane while itis submerged in a bath of water; this measurement may be taken as ameasure of the wet strength of the material. This test is usefullyemployed on a membrane that has been equilibrated in excess water.Materials that exhibit a wet tensile strength in excess of 100 poundsper square inch of cross sectional area are strong solids. Importantly,they are strong solids even in the presence of an excess of water.Clearly, such materials are not soluble in water. Water solublematerials will have no measurable strength when evaluated using themodified procedure of ASTM D412 which has been outlined above. Further,such materials are not dispersed in water. An aqueous dispersion of thepolymer will have no measurable strength when tested using the modifiedprocedure of ASTM D412 as discussed above. The polymer membranes of thepresent invention are not soluble in water and do not form dispersionswhen contacted with an excess of water. The newly discovered polymermembranes have good water vapor transport properties and have tensilestrengths when equilibrated with water in excess of 100 psi. They aresolids even when wet.

A distinguishing feature of the block copolymers of the presentinvention which have been selectively sulfonated in an interior block isthat they can be formed into objects having a useful balance ofproperties that have heretofore been unachievable, including strengtheven when equilibrated with water, water vapor transport behavior,dimensional stability, and processability. The hydrophobic blocks andtheir position at the ends of the block copolymer chain contribute tothe wet strength, dimensional stability and processability of thesepolymers and objects formed from them. The sulfonated block(s)positioned in the interior of the copolymer allow effective water vaportransport. The combined properties afford a unique material. As a resultof the above, the sulfonated block copolymers of the present inventionare capable of being utilized more effectively in a wide variety of usesin which the prior art sulfonated polymers proved deficient due to theweakness of such polymers in water. Note that sulfonated blockcopolymers that are “water soluble” or “water dispersed” by their naturewould not have sufficient tensile strength for the applicationsdisclosed herein.

Accordingly, the present invention broadly comprises sulfonated blockcopolymers for forming articles that are solids in water comprising atleast two polymer end blocks and at least one saturated polymer interiorblock wherein

-   -   a. each end block is a polymer block resistant to sulfonation        and each interior block is a saturated polymer block susceptible        to sulfonation, said end and interior blocks containing no        significant levels of olefinic unsaturation;    -   b. each end block independently having a number average        molecular weight between about 1,000 and about 60,000 and each        interior block independently having a number average molecular        weight between about 10,000 and about 300,000;    -   c. said interior blocks being sulfonated to the extent of 10 to        100 mol percent; and    -   d. said sulfonated, block copolymer when formed into an article        has a tensile strength greater than 100 psi in the presence of        water according to ASTM D412.

Typically, in the sulfonated block copolymer, the mol percentage of endblocks will be sufficient such that the block copolymer will beinsoluble in water and non-dispersible in water. In said blockcopolymer, the mol percent of the end blocks can be greater than 15%,preferably greater than 20%. In other instances, the mol percent of theend blocks can be greater than 20% and less than 70%, preferably greaterthan 20% and less than 50%. The hydrophobic units of the end blockscontribute to the block copolymer's insolubility. Furthermore, if theend block mol percent approaches the lower values, hydrophobicity of theentire block copolymer can be adjusted by incorporating hydrophobicmonomer units into the interior blocks, including A blocks as well as Bblocks.

Throughout the current application with regard to the present invention,the following terms have the following meanings. “Resistant tosulfonation” means that little, if any, sulfonation of the block occurs.“Susceptible to sulfonation” means that sulfonation is very likely tooccur in the blocks referenced. The expression “resistant tosulfonation” as used with regard to the present invention with regard toend blocks and the expression “susceptible to sulfonation” with regardto the interior blocks are meant to express that sulfonation occursprimarily in the interior block(s) of the copolymer so that the degreeof sulfonation which occurs in the interior block(s), relative to thetotal degree of sulfonation of the block copolymer, is in everyinstance, higher than the degree of sulfonation which occurs in the endblocks. The degree of sulfonation in the interior block(s) is at least85% of the total overall sulfonation of the block copolymer. Inalternative embodiments, the degree of sulfonation in the interiorblock(s) is at least 90% of the total sulfonation, with the preferredamount in this embodiment being at least 95% of the total sulfonation.In some embodiments, the end blocks may show no sulfonation. Note thatthroughout the specification there are discussions relating to endblocks and interior blocks. In many instances, the structures related toend blocks represented by “A” and interior blocks represented by “B” areused. Such discussions, unless indicated otherwise, are not intended tobe limited to only those sulfonated block copolymers of the presentinvention that contain “A” end blocks and “B” interior blocks but areinstead intended to be discussions that are representative of allstructures of embodiments of the present invention in which end blocksthat are resistant to sulfonation are represented by “A”, “A1”, or “A2”blocks and interior blocks that are susceptible to sulfonation arerepresented by “B”, “B1”, “B2”, “D”, “E” or “F” blocks. Furthermore,note that in some instances, more than one interior block may besusceptible to sulfonation. In those instances, the blocks may be thesame or they may be different.

In addition, the term “containing no significant levels of unsaturation”means that the residual olefin unsaturation of the block copolymer isless than 2.0 milliequivalents of carbon-carbon double bonds per gram ofpolymer, preferably less than 0.2 milliequivalents of carbon-carbondouble bonds per gram of block copolymer. This means, e.g., that for anyconjugated diene polymer component present in said sulfonated blockcopolymer, that such conjugated diene must be hydrogenated such that atleast 90% of the double bonds are reduced by the hydrogenation,preferably at least 95% of the double bonds are reduced by thehydrogenation, and even more preferably at least 98% of the double bondsare reduced by the hydrogenation.

In one embodiment, the present invention broadly comprises sulfonatedblock copolymers comprising at least two polymer end blocks A and atleast one polymer interior block B wherein

-   -   a. each A block is a polymer block resistant to sulfonation and        each B block is a polymer block susceptible to sulfonation, said        A and B blocks containing no significant levels of olefinic        unsaturation;    -   b. each A block independently having a number average molecular        weight between about 1,000 and about 60,000 and each B block        independently having a number average molecular weight between        about 10,000 and about 300,000;    -   c. each A block comprising one or more segments selected from        polymerized (i) para-substituted styrene monomers, (ii)        ethylene, (iii) alpha olefins of 3 to 18 carbon atoms; (iv)        1,3-cyclodiene monomers, (v) monomers of conjugated dienes        having a vinyl content less than 35 mol percent prior to        hydrogenation, (vi) acrylic esters, (vii) methacrylic esters,        and (viii) mixtures thereof, wherein any segments containing        polymerized 1,3-cyclodiene or conjugated dienes are subsequently        hydrogenated and wherein any A block comprising polymerized        ethylene or hydrogenated polymers of a conjugated, acyclic diene        have a melting point greater than 50° C., preferably greater        than 80° C.;    -   d. each B block comprising segments of one or more vinyl        aromatic monomers selected from polymerized (i) unsubstituted        styrene monomers, (ii) ortho-substituted styrene monomers, (iii)        meta-substituted styrene monomers, (iv) alpha-methylstyrene, (v)        1,1-diphenylethylene, (vi) 1,2-diphenylethylene and (vii)        mixtures thereof;    -   e. wherein said B blocks are sulfonated to the extent of 10 to        100 mol percent, based on the units of vinyl aromatic monomer in        said B blocks;    -   f. the mol percent of vinyl aromatic monomers which are        unsubstituted styrene monomers, ortho-substituted styrene        monomers, meta-substituted styrene monomers,        alpha-methylstyrene, 1,1-diphenylethylene and        1,2-diphenylethylene in each B block is between 10 mol percent        and 100 mol percent; and    -   g. said sulfonated block copolymer when formed into an article        has a tensile strength greater than 100 psi in the presence of        water according to ASTM D412.

In this embodiment, the A blocks may also contain up to 15 mol percentof monomers mentioned for the B blocks. Such sulfonated block copolymersof this embodiment may be represented by the structures A-B-A,(A-B-A)nX, (A-B)nX or mixtures thereof, where n is an integer from 2 toabout 30, X is a coupling agent residue, and A and B are as definedhereinabove.

In another embodiment, the present invention relates to a sulfonatedblock copolymer comprising polymer blocks A1, A2, B1 and B2, having thestructure (A1-B1-B2)nX, (A1-B2-B1)nX, (A2-B1-B2)nX, (A2-B2-B1)nX,(A1-A2-B1)nX, (A1-A2-B2)nX, (A2-A1-B1)nX, (A2-A1-B2)nX, (A1-A2-B1-B2)nX,(A1-A2-B2-B1)nX, (A2-A1-B1-B2)nX or (A2-A1-B2-B1)nX, where n is aninteger from 2 to 30 and X is a coupling agent residue, and wherein:

-   -   a. each A1 block and each A2 block is a polymer block resistant        to sulfonation and each B1 and each B2 block is a polymer block        susceptible to sulfonation, said A1, A2, B1 and B2 blocks        containing no significant levels of olefinic unsaturation;    -   b. each A1 block and each A2 block independently having a number        average molecular weight between about 1,000 and about 60,000        and each B1 and B2 block independently having a number average        molecular weight between about 10,000 and about 300,000;    -   c. each A1 block is selected from the group consisting of        polymerized (i) ethylene, and (ii) conjugated dienes having a        vinyl content less than 35 mol percent prior to hydrogenation        wherein the conjugated dienes are subsequently hydrogenated;    -   d. each A2 block being selected from the group consisting of        polymerized (i) para-substituted styrene monomers, and (ii)        1,3-cyclodiene monomers wherein the 1,3-cyclodiene monomers are        subsequently hydrogenated;    -   e. each B1 block comprising segments of one or more vinyl        aromatic monomers selected from polymerized (i) unsubstituted        styrene monomers, (ii) ortho-substituted styrene monomers, (iii)        meta-substituted styrene monomers, (iv) alpha-methylstyrene, (v)        1,1-diphenylethylene, (vi) 1,2-diphenylethylene and (vii)        mixtures thereof;    -   f. each B2 block being hydrogenated, copolymerized segments of        at least one conjugated diene and at least one mono alkenyl        arene selected from (i) unsubstituted styrene monomers, (ii)        ortho-substituted styrene monomers, (iii) meta-substituted        styrene monomers, (iv) alpha-methylstyrene, (v)        1,1-diphenylethylene, (vi) 1,2-diphenylethylene and (vii)        mixtures thereof;    -   g. each B1 and each B2 block being sulfonated to the extent of        10 to 100 mol percent; and    -   h. said sulfonated block copolymer when formed into an article        has a tensile strength greater than 100 psi in the presence of        water according to ASTM D412.

In still another aspect, the present invention includes sulfonated blockcopolymers also containing at least one block D having a glasstransition temperature of less than 20° C. One such block comprises ahydrogenated polymer or copolymer of a conjugated diene selected fromisoprene, 1,3-butadiene and mixtures thereof having a vinyl contentprior to hydrogenation of between 20 and 80 mol percent and a numberaverage molecular weight of between about 1000 and about 50,000. Anotherblock D could comprise a polymer of an acrylate monomer or a siliconepolymer having a number average molecular weight of between about 1000and about 50,000. Another block D could be polymerized isobutylenehaving a number average molecular weight of between about 1,000 andabout 50,000. In this embodiment, the present invention includes asulfonated, block copolymer having the general configuration A-D-B-D-A,A-B-D-B-A, (A-D-B)nX, (A-B-D)nX, or mixtures thereof, where n is aninteger from 2 to about 30, and X is coupling agent residue wherein:

-   -   a. each A block and each D block is a polymer block resistant to        sulfonation and each B block is a polymer block susceptible to        sulfonation, said A, B and D blocks containing no significant        levels of olefinic unsaturation;    -   b. each A block independently having a number average molecular        weight between about 1,000 and about 60,000, each D block        independently having a number average molecular weight between        about 1000 and about 50,000 and each B block independently        having a number average molecular weight between about 10,000        and about 300,000;    -   c. each A block comprises one or more segments selected from        polymerized (i) para-substituted styrene monomers, (ii)        ethylene, (iii) alpha olefins of 3 to 18 carbon atoms; (iv)        1,3-cyclodiene monomers, (v) monomers of conjugated dienes        having a vinyl content less than 35 mol percent prior to        hydrogenation, (vi) acrylic esters, (vii) methacrylic esters,        and (viii) mixtures thereof, wherein any segments containing        polymerized 1,3-cyclodiene or conjugated dienes are subsequently        hydrogenated;    -   d. each B block comprises segments of one or more vinyl aromatic        monomers selected from polymerized (i) unsubstituted styrene        monomers, (ii) ortho-substituted styrene monomers, (iii)        meta-substituted styrene monomers, (iv) alpha-methylstyrene, (v)        1,1-diphenylethylene, (vi) 1,2-diphenylethylene and (vii)        mixtures thereof;    -   e. each D block comprises polymers having a glass transition        temperature less than 20° C. and a number average molecular        weight of between about 1,000 and about 50,000, said D block        being selected from the group consisting of (i) a polymerized or        copolymerized conjugated diene selected from isoprene,        1,3-butadiene having a vinyl content prior to hydrogenation of        between 20 and 80 mol percent, (ii) a polymerized acrylate        monomer, (iii) polymerized silicon, (iv) polymerized isobutylene        and (v) mixtures thereof, wherein any segments containing        polymerized 1,3-butadiene or isoprene are subsequently        hydrogenated, and has a glass transition temperature of less        than 20° C.;    -   f. wherein said B blocks are sulfonated to the extent of 10 to        100 mol percent, based on the units of vinyl aromatic monomer in        said B blocks;    -   g. the mol percent of vinyl aromatic monomers which are        unsubstituted styrene monomers, ortho-substituted styrene        monomers, meta-substituted styrene monomers,        alpha-methylstyrene, 1,1-diphenylethylene and        1,2-diphenylethylene in each B block being between 10 mol        percent and 100 mol percent; and    -   h. said sulfonated block copolymer when formed into an article        has a tensile strength greater than 100 psi in the presence of        water according to ASTM D412.

In a further alternative of this embodiment, the present inventionincludes sulfonated block copolymers which have more than one D blockand in which the second D block is polymerized acrylate monomer orpolymerized silicon polymer.

In a further embodiment, the present invention includes block copolymersfor forming articles that are solids in water comprising at least twopolymer end blocks A and at least one polymer interior block B wherein:

-   -   a. each A block is a polymer block containing essentially no        sulfonic acid or sulfonate functional groups and each B block is        a polymer block containing 10 to 100 mol percent sulfonic acid        or sulfonate functional groups based on the number of monomer        units of the B block, said A and B blocks containing no        significant levels of olefinic unsaturation; and    -   b. each A block independently having a number average molecular        weight between about 1,000 and about 60,000 and each B block        independently having a number average molecular weight between        about 10,000 and about 300,000.

In a further embodiment of the present invention, the monomerscomprising the B block directly above are sulfonic functional monomers.In a preferred embodiment, the monomers are selected from the groupconsisting of sodium p-styrenesulfonate, lithium p-styrenesulfonate,potassium p-styrenesulfonate, ammonium p-styrenesulfonate, aminep-styrenesulfonate, ethyl p-styrenesulfonate, sodium methallylsulfonate,sodium allylsulfonate, sodium vinylsulfonate and mixtures thereof.

In a still further aspect, the present invention relates to sulfonatedblock copolymers wherein a portion of the sulfonic functional groupshave been neutralized with an ionizable metal compound to form metalsalts.

An even further embodiment of the present invention comprises asulfonated block copolymer comprising at least two polymer end blocks A,at least one polymer interior blocks E, and at least one polymerinterior block F, having the structure A-E-F-E-A, A-F-E-F-A, (A-F-E)nXor (A-E-F)nX, where n is an integer from 2 to 30 and X is a couplingagent residue, and wherein:

-   -   a. each A block is a polymer block resistant to sulfonation and        each E and F block is a polymer block susceptible to        sulfonation, said A, E and F blocks containing no significant        levels of olefinic unsaturation;    -   b. each A block independently having a number average molecular        weight between about 1,000 and about 60,000 and each E and F        block independently having a number average molecular weight        between about 10,000 and about 300,000;    -   c. each A block comprises one or more segments selected from        polymerized (i) para-substituted styrene monomers, (ii)        ethylene, (iii) alpha olefins of 3 to 18 carbon atoms; (iv)        1,3-cyclodiene monomers, (v) monomers of conjugated dienes        having a vinyl content less than 35 mol percent prior to        hydrogenation, (vi) acrylic esters, (vii) methacrylic esters,        and (viii) mixtures thereof, wherein any segments containing        polymerized 1,3-cyclodiene or conjugated dienes are subsequently        hydrogenated;    -   d. each F block comprising segments of one or more vinyl        aromatic monomers selected from polymerized (i) unsubstituted        styrene monomers, (ii) ortho-substituted styrene monomers, (iii)        meta-substituted styrene monomers, (iv) alpha-methylstyrene, (v)        1,1-diphenylethylene, (vi) 1,2-diphenylethylene and (vii)        mixtures thereof;    -   e. each E block is a copolymerized hydrogenated block of at        least one conjugated diene and at least one mono alkenyl arene        selected from (i) unsubstituted styrene monomers, (ii)        ortho-substituted styrene monomers, (iii) meta-substituted        styrene monomers, (iv) alpha-methylstyrene, (v)        1,1-diphenylethylene, (vi) 1,2-diphenylethylene and (vii)        mixtures thereof;    -   f. wherein said E and F blocks are sulfonated to the extent of        10 to 100 mol percent, based on the units of vinyl aromatic        monomer in said E and F blocks; and    -   g. said sulfonated block copolymer when formed into an article        has a tensile strength greater than 100 psi in the presence of        water according to ASTM D412.

In a preferred alternative to this embodiment, the A block is a polymerblock of para-tert-butylstyrene, the F block is a polymer block ofunsubstituted styrene, and the E block is a copolymer block ofhydrogenated 1,3-butadiene and unsubstituted styrene.

Applicants also claim as their invention processes for making thesulfonated block copolymers of the present invention. One of theprocesses for preparing the sulfonated block copolymers comprisesreacting a block copolymer with a sulfonation reagent that selectivelysulfonates the B blocks of a block copolymer comprising at least twopolymer end blocks A and at least one polymer interior block B wherein:

-   -   a. each A block is a polymer block resistant to sulfonation and        each B block is a polymer block susceptible to sulfonation, said        A and B blocks containing no significant levels of olefinic        unsaturation;    -   b. each A block independently having a number average molecular        weight between about 1,000 and about 60,000 and each B block        independently having a number average molecular weight between        about 10,000 and about 300,000, wherein the mole percent of A        end blocks is 20 to 50 percent;    -   c. said B blocks are sulfonated to the extent of 10 to 100 mol        percent; and    -   d. said sulfonated block copolymer having a tensile strength        greater than 100 psi in the presence of water according to ASTM        D412.

Another process comprises preparing sulfonated block copolymers forforming articles that are solids in water having at least two polymerend blocks A and at least one polymer interior block B, the processcomprising sulfonating said interior block B until said block B issubstantially sulfonated, and wherein:

-   -   a. each said A block is other than solely polymers of ethylene        or solely hydrogenated polymers of conjugated dienes;    -   b. wherein said block copolymer is water insoluble; and    -   c. wherein said end blocks A have essentially no sulfonated        monomers.

In one particularly preferred embodiment of the present invention, thesulfonation agent utilized is an acyl sulfate, and in a particularlypreferred alternative embodiment, the sulfonation agent utilized issulfur trioxide.

Any number of precursor molecules may be utilized in the preparation ofthe sulfonated block copolymers of the present invention. In onepreferred embodiment of the present invention, the precursor blockcopolymer, prior to hydrogenation, has the general configuration A-B-A,(A-B-A)nX, (A-B)nX, A-D-B-D-A, A-B-D-B-A, (A-D-B)nX, (A-B-D)nX ormixtures thereof, where n is an integer from 2 to about 30, and X is acoupling agent residue and wherein:

-   -   a. each A block is a polymer block resistant to sulfonation,        each D block is a polymer block resistant to sulfonation, and        each B block is a polymer block susceptible to sulfonation, said        A, D and B blocks containing no significant levels of olefinic        unsaturation;    -   b. each A block independently having a number average molecular        weight between about 1,000 and about 60,000, each D block        independently having a number average molecular weight between        about 1,000 and about 50,000, and each B block independently        having a number average molecular weight between about 10,000        and about 300,000;    -   c. each A block comprises one or more segments selected from        polymerized (i) para-substituted styrene monomers, (ii)        ethylene, (iii) alpha olefins of 3 to 18 carbon atoms; (iv)        1,3-cyclodiene monomers, (v) monomers of conjugated dienes        having a vinyl content less than 35 mol percent prior to        hydrogenation, (vi) acrylic esters, (vii) methacrylic esters,        and (viii) mixtures thereof;    -   d. each B block comprises segments of one or more vinyl aromatic        monomers selected from polymerized (i) unsubstituted styrene        monomers, (ii) ortho-substituted styrene monomers, (iii)        meta-substituted styrene monomers, (iv) alpha-methylstyrene, (v)        1,1-diphenylethylene, (vi) 1,2-diphenylethylene and (vii)        mixtures thereof;    -   e. each D block comprises polymers having a glass transition        temperature less than 20° C. and a number average molecular        weight of between about 1000 and about 50,000, said D block        being selected from the group consisting of (i) a polymerized or        copolymerized conjugated diene selected from isoprene,        1,3-butadiene having a vinyl content prior to hydrogenation of        between 20 and 80 mol percent, (ii) a polymerized acrylate        monomer, (iii) polymerized silicon, (iv) polymerized isobutylene        and (v) mixtures thereof, wherein any segments containing        polymerized 1,3-butadiene or isoprene are subsequently        hydrogenated; and    -   f. the mol percent of vinyl aromatic monomers which are        unsubstituted styrene monomers, ortho-substituted styrene        monomers, meta-substituted styrene monomers,        alpha-methylstyrene, 1,1-diphenylethylene and        1,2-diphenylethylene in each B block is between 10 mol percent        and 100 mol percent.

In another preferred embodiment of the present invention, the precursorblock copolymer, prior to hydrogenation, has the general configuration(A1-B1-B2)nX, (A1-B2-B1)nX, (A2-B1-B2)nX, (A2-B2-B1)nX, (A1-A2-B1)nX,(A1-A2-B2)nX, (A2-A1-B1)nX, (A2-A1-B2)nX, (A1-A2-B1-B2)nX,(A1-A2-B2-B1)nX, (A2-A1-B1-B2)nX or (A2-A1-B2-B1)nX, where n is aninteger from 2 to 30 and X is a coupling agent residue, and wherein:

-   -   a. each A1 block and each A2 block is a polymer block resistant        to sulfonation and each B1 and each B2 block is a polymer block        susceptible to sulfonation, said A1, A2, B1 and B2 blocks        containing no significant levels of olefinic unsaturation;    -   b. each A1 block and each A2 block independently having a number        average molecular weight between about 1,000 and about 60,000        and each B1 and B2 block independently having a number average        molecular weight between about 10,000 and about 300,000;    -   c. each A1 block is selected from the group consisting of        polymerized (i) ethylene, and (ii) conjugated dienes having a        vinyl content less than 35 mol percent prior to hydrogenation;    -   d. each A2 block being selected from the group consisting of        polymerized (i) para-substituted styrene monomers, and (ii)        1,3-cyclodiene monomers;    -   e. each B1 block comprising segments of one or more vinyl        aromatic monomers selected from polymerized (i) unsubstituted        styrene monomers, (ii) ortho-substituted styrene monomers, (iii)        meta-substituted styrene monomers, (iv) alpha-methylstyrene, (v)        1,1-diphenylethylene, (vi) 1,2-diphenylethylene and (vii)        mixtures thereof;    -   f. each B2 block being polymerized segments of at least one        conjugated diene and at least one mono alkenyl arene selected        from (i) unsubstituted styrene monomers, (ii) ortho-substituted        styrene monomers, (iii) meta-substituted styrene monomers, (iv)        alpha-methylstyrene, (v) 1,1-diphenylethylene, (vi)        1,2-diphenylethylene and (vii) mixtures thereof;    -   and    -   g. each B1 and each B2 block is sulfonated to the extent of 10        to 100 mol percent.

Still another class of precursors include those of the generalconfiguration A-E-F-E-A or (A-E-F)nX, where n is an integer from 2 to 30and X is a coupling agent residue, and wherein:

-   -   a. each A block is a polymer block resistant to sulfonation and        each E and F block is a polymer block susceptible to        sulfonation, said A, E and F blocks containing no significant        levels of olefinic unsaturation;    -   b. each A block independently having a number average molecular        weight between about 1,000 and about 60,000 and each E and F        block independently having a number average molecular weight        between about 10,000 and about 300,000;    -   c. each A block being selected from the group consisting of        polymerized (i) para-substituted styrene monomers;    -   d. each F block comprising segments of one or more vinyl        aromatic monomers selected from polymerized (i) unsubstituted        styrene monomers, (ii) ortho-substituted styrene monomers, (iii)        meta-substituted styrene monomers, (iv) alpha-methylstyrene, (v)        1,1-diphenylethylene, (vi) 1,2-diphenylethylene and (vii)        mixtures thereof;    -   e. each E block is a polymerized block of at least one        conjugated diene and at least one mono alkenyl arene selected        from (i) unsubstituted styrene monomers, (ii) ortho-substituted        styrene monomers, (iii) meta-substituted styrene monomers, (iv)        alpha-methylstyrene, (v) 1,1-diphenylethylene, (vi)        1,2-diphenylethylene and (vii) mixtures thereof;    -   and    -   f. wherein said E and F blocks are sulfonated to the extent of        10 to 100 mol percent, based on the units of vinyl aromatic        monomer in said E and F blocks.

Those of ordinary skill in the art will recognize that the above notedstructures listed are not necessarily intended to be an exhaustive listof possible precursors for preparing the block copolymers of the presentinvention. The above precursors can be used as the starting materials inthe process for preparing the sulfonated block copolymers of the presentinvention utilizing the process set forth hereinbefore as well as anyother process that is readily available in the art provided that thefinal product meets the requirements of the present invention. Theserequirements include that the sulfonated block copolymer be a solid inthe presence of water, the interior block(s) contain one or moresulfonic functional groups after sulfonation and the sulfonated blockcopolymer when formed into an article has a tensile strength greaterthan 100 psi in the presence of water according to ASTM D412.

In still another aspect, the present invention comprises an articleformed at least in part from a composition comprising the inventivesulfonated block copolymer. In particular, the present inventioncontemplates articles, such as, for example, fuel cells, proton exchangemembranes for fuel cells, dispersions of metal impregnated carbonparticles in sulfonated polymer cement for use in an electrodeassemblies, including electrode assemblies for fuel cells, fabrics,coated fabrics, surgical supplies and devices, filtration membranes, airconditioning membranes, heat recovery membranes, desalination membranes,adhesives, personal hygiene articles, super absorbent articles, bindersfor super absorbents and antifouling coatings. Specific examples of sucharticles include, but are not limited to, selective, permeabilitymembranes formed in part from a composition comprising the sulfonatedblock copolymer. Other uses include fibers, tubes, fabrics, sheets,coatings for woven and non-woven fabrics and laminates. Specificapplications include, but are not limited to, breathable protectiveclothing and gloves for first responders, firefighters, chemical andbiological workers, agricultural workers, medical employees, andmilitary personnel involved in handling potentially hazardous materials;sports and recreational clothing; tenting; selective membranes forindustrial, medical and water purification applications; and systemswhich avoid moisture build up inside the walls and between the floor andfoundation of a house. Other specific applications are in personalhygiene, including use as super absorbents or binders for superabsorbents in diapers or incontinence products. Still other specificapplications include marine coatings and anti-fouling coatings ingeneral. Yet other applications include coatings for membranes, such ascoatings on polysulfone desalination membranes.

In yet another aspect, the present invention includes a fuel cellincorporating one or more membranes made from the sulfonated blockcopolymers of the present invention. More specifically, the presentinvention includes a fuel cell comprising:

-   -   a. a membrane made from the sulfonated block copolymer;    -   b. first and second opposed electrodes in contact with said        membrane;    -   c. means for supplying a fuel to said first electrode; and    -   d. means for permitting an oxidant to contact said second        electrode.

Without wishing to be bound to a particular theory, the inventorsbelieve that the significance of the present invention depends upon twostructural features of the block copolymers: 1) the striking polaritydifferences between the outer A blocks and the interior B blocksregulate the physics a) of phase separation of the blocks of thecopolymers, b) of water transportation through the membranes, and c) ofthe barrier properties of these polymers to species other than water andprotons; and 2) the strength and dimensional stability of materialsprepared from these polymers depends on the A blocks having no or verylittle functionality. The polarity of the B interior blocks derives fromthe sulfonation of the vinyl aromatic moieties enchained in the Binterior block segments(s). In the solid phase, these aromatic sulfonicacid species (−503H centers) self assemble into a continuous, polarphase that is extremely hydrophilic. This phase affords a ready pathwayfor protons or water to pass from one side of the membrane to the other.The greater is the density of —SO3H sites in this phase (mol of —SO3H/gof block copolymer), the faster is the transport of water moleculesthrough the composite material. These pathways might be thought of asmicrophase separated ion or water channels that are approximately ten toa few thousand angstroms wide. In this multi-phase material, thesechannels are constrained by a non-polar, hydrophobic phase, which iscomposed of the hydrophobic A blocks of the copolymer. As the A blockscontain no or very few reactive centers, following sulfonation the Ablocks have no or very little sulfonic acid functionality. As a resultand in contrast to the B interior blocks, the A blocks are veryresistant to permeation by water or protonic species. The properties ofthe A block phase of the multi-phasic material are not readily affectedby the addition of protonic materials or water. For this reason, thenon-polar A block phase of the copolymer material is not significantlyweakened by the addition of water. By example with regard to oneembodiment of the present invention, as each B interior block ischemically attached to two A block outer segments, the composite,multiphasic material has substantial strength in the wet state, as well.In fact, a comparison of the strength of a film or membrane preparedfrom a selectively sulfonated block copolymer tested while wet versusits strength when tested while dry is a good measure of the absence (ornear absence) of functionality in the A block of the copolymer; the wetstrength should be at least more than 30% of the strength of the drysample.

Furthermore, the non-polar, hydrophobic phase may be continuousaffording a co-continuous multi-phase structure. When this is the case,the strength of this phase and its resistance to swelling in thepresence of water, controls and limits the level of swelling that canoccur in the hydrophilic phase. In this way, the dimensional stabilityof the fabricated part is controlled. Even if the hydrophobic A blockphase is dispersed, the strength of that phase constrains the swellingof the hydrophilic phase to the limit defined by the extendibility ofthe sulfonated B blocks in water. As the ends of the B blocks aretethered to A blocks that are not plasticized by water, they can onlyswell to the extent defined by their chain length. Swelling cannotovercome the strength of the chemical bond that holds the A and B blocks(outer and interior blocks) together.

The material properties—hardness, strength, rigidity, and temperatureresistance—of composites prepared from these block copolymers will bestrongly affected by the nature of the A block polymer(s) and thecontinuity, or lack thereof, of the hydrophobic phase. On the otherhand, the water and proton transport properties, elasticity,flexibility, and toughness of these materials will be strongly affectedby the nature of the B block polymer or copolymer of the multi-phasematerial. Depending upon the choice of monomer(s) used in making theinterior segment of the block copolymer, the selectively, sulfonated,block copolymer may afford a very elastic and soft material, or a verytough but stiff material can be formed. As water acts to plasticize theinteractions of the sulfonated moieties in the hydrophilic phase, theaddition of water to these composites will tend to soften them—to makethem less stiff.

The barrier properties of these materials are affected by the propertiesof both the hydrophilic and hydrophobic phases of the composite. Thepermeation of non-polar gases and non-polar liquids is greatlyrestricted by the high polarity and cohesive energy of the hydrophilicphase. Also, the hydrophilic phase must be continuous or co-continuous.The hydrophobic phase optionally may not be continuous in which casethere is no continuity for the flow of molecules through the non-polarphase. When the hydrophobic phase is co-continuous with the ionchannels, the density (non-porous solid) of the hydrophobic phaseimpedes the diffusion molecules through that phase of the material.

Block copolymers having sulfonation resistant outer segments, A blocks,and sulfonation susceptible interior segments, saturated B blocks, maybe selectively sulfonated to afford materials having a unique two-phasestructure. A consequence of this structure is that non-crosslinkedpolymers having a unique balance of useful properties—good dimensionalstability, surprising water transport rates, and surprising strength inthe presence of water—may be formed. The specific balance of propertiesneeded for a particular application may be tuned by adjusting the natureor dimensions of the A and B blocks of the copolymer, the level ofsulfonation of the polymer, the linearity or degree of branching in thestarting polymer before sulfonation, and the amount of neutralization,if any, of the —SO3H sites. The need for materials having these types ofproperties is great. Myriad applications for films, membranes, fibers toinclude non-woven fibers, coatings, adhesives, molded articles and thelike have been identified. The use of these articles to provideprotection against chemical and biological agents, to purify aqueousstreams, to guard against fungal and microbial growth, to allowevaporative cooling by transport of water (particularly from sweating)to a surface, to enhance the absorption of radiant energy when wet, andto soak up water are envisioned. The breadth of utility of thisinvention therefore appears to be large.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a comparison of the storage modulus of sample T-3 beforeand after sulfonation. This figure shows that the midpoint of the glassto rubber transition, Tg, of the S/EB interior block moves fromapproximately 15° C. to approximately 50° C.

FIG. 2 shows a similar increase in the Tg of the interior block ofsample T-2. These increases demonstrate that in both samples theinterior block is sulfonated to a degree that results in a significantchange in the physical properties of the sample.

FIG. 3 shows the structure of films cast from: (left) 90/10toluene/methanol, (center) 80/20 THF/toluene, and (right) 50/50THF/toluene as imaged with AFM.

FIG. 4 displays DSC plots showing differences in the melting of water asa function of casting solutions.

DETAILED DESCRIPTION OF THE INVENTION

The base polymers needed to prepare the sulfonic acid containing blockcopolymers of the present invention may be made by a number of differentprocesses, including anionic polymerization, moderated anionicpolymerization, cationic polymerization, Ziegler-Natta polymerization,and living or stable free radical polymerization. Anionic polymerizationis described below in the detailed description, and in the patentsreferenced. Moderated anionic polymerization processes for makingstyrenic block copolymers have been disclosed, for example, in U.S. Pat.Nos. 6,391,981, 6,455,651 and 6,492,469, each incorporated herein byreference. Cationic polymerization processes for preparing blockcopolymers are disclosed, for example, in U.S. Pat. Nos. 6,515,083 and4,946,899, each incorporated herein by reference. Living Ziegler-Nattapolymerization processes that can be used to make block copolymers wererecently reviewed by G. W. Coates, P. D. Hustad, and S. Reinartz inAngew. Chem. Int. Ed., 2002, 41, 2236-2257; a subsequent publication byH. Zhang and K. Nomura (JACS Communications, 2005) describes the use ofliving Z-N techniques for making styrenic block copolymers specifically.The extensive work in the field of nitroxide mediated living radicalpolymerization chemistry has been reviewed; see C. J. Hawker, A. W.Bosman, and E. Harth, Chemical Reviews, 101(12), pp. 3661-3688 (2001).As outlined in this review, styrenic block copolymers could be madeusing living or stable free radical techniques. For the polymers of thepresent invention, nitroxide mediated polymerization methods will be thepreferred living or stable free radical polymerization process.

1. Polymer Structure

One of the important aspects of the present invention relates to thestructure of the sulfonated block copolymers. In one embodiment, theseblock copolymers made by the present invention will have at least twopolymer end or outer blocks A and at least one saturated polymerinterior block B wherein each A block is a polymer block resistant tosulfonation and each B block is a polymer block susceptible tosulfonation.

Preferred structures have the general configuration A-B-A, (A-B)n(A),(A-B-A)n, (A-B-A)nX, (A-B)nX, A-B-D-B-A, A-D-B-D-A, (A-D-B)n(A),(A-B-D)n(A), (A-B-D)nX, (A-D-B)nX or mixtures thereof, where n is aninteger from 2 to about 30, X is coupling agent residue and A, B and Dare as defined hereinbefore.

Most preferred structures are either the linear A-B-A, (A-B)2X,(A-B-D)nX 2X and (A-D-B)nX 2X structures or the radial structures(A-B)nX and (A-D-B)nX where n is 3 to 6. Such block copolymers aretypically made via anionic polymerization, cationic polymerization orZiegler-Natta polymerization. Preferably, the block copolymers are madevia anionic polymerization. It is recognized that in any polymerization,the polymer mixture will include a certain amount of A-B diblockcopolymer, in addition to any linear and/or radial polymers.

The A blocks are one or more segments selected from polymerized (i)para-substituted styrene monomers, (ii) ethylene, (iii) alpha olefins of3 to 18 carbon atoms; (iv) 1,3-cyclodiene monomers, (v) monomers ofconjugated dienes having a vinyl content less than 35 mol percent priorto hydrogenation, (vi) acrylic esters, (vii) methacrylic esters, and(viii) mixtures thereof. If the A segments are polymers of1,3-cyclodiene or conjugated dienes, the segments will be hydrogenatedsubsequent to polymerization.

The para-substituted styrene monomers are selected frompara-methylstyrene, para-ethylstyrene, para-n-propylstyrene,para-iso-propylstyrene, para-n-butylstyrene, para-sec-butylstyrene,para-iso-butylstyrene, para-t-butylstyrene, isomers ofpara-decylstyrene, isomers of para-dodecylstyrene and mixtures of theabove monomers. Preferred para-substituted styrene monomers arepara-t-butylstyrene and para-methylstyrene, with para-t-butylstyrenebeing most preferred. Monomers may be mixtures of monomers, depending onthe particular source. It is desired that the overall purity of thepara-substituted styrene monomers be at least 90% wt, preferably atleast 95% wt, and even more preferably at least 98% wt of the desiredpara-substituted styrene monomer.

When the A blocks are polymers of ethylene, it may be useful topolymerize ethylene via a Ziegler-Natta process, as taught in thereferences in the review article by G. W. Coates et. al, as cited above,which disclosure is herein incorporated by reference. It is preferred tomake the ethylene blocks using anionic polymerization techniques astaught in U.S. Pat. No. 3,450,795, which disclosure is hereinincorporated by reference. The block molecular weight for such ethyleneblocks will typically be between about 1,000 and about 60,000.

When the A blocks are polymers of alpha olefins of 3 to 18 carbon atoms,such polymers are prepared by via a Ziegler-Natta process, as taught inthe references in the review article by G. W. Coates et. al, as citedabove, which disclosure is herein incorporated by reference. Preferablythe alpha olefins are propylene, butylene, hexane or octene, withpropylene being most preferred. The block molecular weight for suchalpha olefin blocks will typically be between about 1,000 and about60,000.

When the A blocks are hydrogenated polymers of 1,3-cyclodiene monomers,such monomers are selected from the group consisting of1,3-cyclohexadiene, 1,3-cycloheptadiene and 1,3-cyclooctadiene.Preferably, the cyclodiene monomer is 1,3-cyclohexadiene. Polymerizationof such cyclodiene monomers is disclosed in U.S. Pat. No. 6,699,941,which disclosure is herein incorporated by reference. It will benecessary to hydrogenate the A blocks when using cyclodiene monomerssince unhydrogenated polymerized cyclodiene blocks would be susceptibleto sulfonation.

When the A blocks are hydrogenated polymers of conjugated acyclic dieneshaving a vinyl content less than 35 mol percent prior to hydrogenation,it is preferred that the conjugated diene is 1,3-butadiene. It isnecessary that the vinyl content of the polymer prior to hydrogenationbe less than 35 mol percent, preferably less than 30 mol percent. Incertain embodiments, the vinyl content of the polymer prior tohydrogenation will be less than 25 mol percent, even more preferablyless than 20 mol percent, and even less than 15 mol percent with one ofthe more advantageous vinyl contents of the polymer prior tohydrogenation being less than 10 mol percent. In this way, the A blockswill have a crystalline structure, similar to that of polyethylene. SuchA block structures are disclosed in U.S. Pat. Nos. 3,670,054 and4,107,236, which disclosures are herein incorporated by reference.

The A blocks may also be polymers of acrylic esters or methacrylicesters. These polymer blocks may be made according to the methodsdisclosed in U.S. Pat. No. 6,767,976, which disclosure is hereinincorporated by reference. Specific examples of the methacrylic esterinclude esters of a primary alcohol and methacrylic acid, such as methylmethacrylate, ethyl methacrylate, propyl methacrylate, n-butylmethacrylate, isobutyl methacrylate, hexyl methacrylate, 2-ethylhexylmethacrylate, dodecyl methacrylate, lauryl methacrylate, methoxyethylmethacrylate, dimethylaminoethyl methacrylate, diethylaminoethylmethacrylate, glycidyl methacrylate, trimethoxysilylpropyl methacrylate,trifluoromethyl methacrylate, trifluoroethyl methacrylate; esters of asecondary alcohol and methacrylic acid, such as isopropyl methacrylate,cyclohexyl methacrylate and isobornyl methacrylate; and esters of atertiary alcohol and methacrylic acid, such as tert-butyl methacrylate.Specific examples of the acrylic ester include esters of a primaryalcohol and acrylic acid, such as methyl acrylate, ethyl acrylate,propyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl acrylate,2-ethylhexyl acrylate, dodecyl acrylate, lauryl acrylate, methoxyethylacrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate,glycidyl acrylate, trimethoxysilylpropyl acrylate, trifluoromethylacrylate, trifluoroethyl acrylate; esters of a secondary alcohol andacrylic acid, such as isopropyl acrylate, cyclohexyl acrylate andisobornyl acrylate; and esters of a tertiary alcohol and acrylic acid,such as tert-butyl acrylate. If necessary, as raw material or rawmaterials, one or more of other anionic polymerizable monomers may beused together with the (meth)acrylic ester in the present invention.Examples of the anionic polymerizable monomer that can be optionallyused include methacrylic or acrylic monomers such as trimethylsilylmethacrylate, N-isopropylmethacrylamide, N-tert-butylmethacrylamide,trimethylsilyl acrylate, N-isopropylacrylamide, andN-tert-butylacrylamide. Moreover, there may be used a multifunctionalanionic polymerizable monomer having in the molecule thereof two or moremethacrylic or acrylic structures, such as methacrylic ester structuresor acrylic ester structures (for example, ethylene glycol diacrylate,ethylene glycol dimethacrylate, 1,4-butanediol diacrylate,1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanedioldimethacrylate, trimethylolpropane triacrylate and trimethylolpropanetrimethacrylate).

In the polymerization processes used to make the acrylic or methacrylicester polymer blocks, only one of the monomers, for example, the(meth)acrylic ester may be used, or two or more thereof may be used incombination. When two or more of the monomers may be used incombination, any copolymerization form selected from random, block,tapered block and the like copolymerization forms may be effected byselecting conditions such as a combination of the monomers and thetiming of adding the monomers to the polymerization system (for example,simultaneous addition of two or more monomers, or separate additions atintervals of a given time).

The A blocks may also contain up to 15 mol percent of the vinyl aromaticmonomers mentioned for the B blocks. In some embodiments, the A blocksmay contain up to 10 mol percent, preferably they will contain only upto 5 mol percent, and particularly preferably only up to 2 mol percentof the vinyl aromatic monomers mentioned in the B blocks. However, inthe most preferred embodiments, the A blocks will contain no vinylmonomers mentioned in the B blocks. Accordingly, the sulfonation levelin the A blocks may be from 0 up to 15 mol percent of the total monomersin the A block. Note that the ranges can include all combinations of molpercents listed herewith.

With regard to the saturated B blocks, each B block comprises segmentsof one or more polymerized vinyl aromatic monomers selected fromunsubstituted styrene monomer, ortho-substituted styrene monomers,meta-substituted styrene monomers, alpha-methylstyrene monomer,1,1-diphenylethylene monomer, 1,2-diphenylethylene monomer, and mixturesthereof. In addition to the monomers and polymers noted immediatelybefore, the B blocks may also comprise a hydrogenated copolymer of suchmonomer (s) with a conjugated diene selected from 1,3-butadiene,isoprene and mixtures thereof, having a vinyl content of between 20 and80 mol percent. These copolymers with hydrogenated dienes may be randomcopolymers, tapered copolymers, block copolymers or controlleddistribution copolymers. Accordingly, there are two preferredstructures: one in which the B blocks are hydrogenated and comprise acopolymer of conjugated dienes and the vinyl aromatic monomers noted inthis paragraph, and another in which the B blocks are unsubstitutedstyrene monomer blocks which are saturated by virtue of the nature ofthe monomer and do not require the added process step of hydrogenation.The B blocks having a controlled distribution structure are disclosed inU.S. Published Patent Application No. 2003/0176582, which disclosure isherein incorporated by reference. U.S. Published Patent Application No.2003/0176582 also discloses the preparation of sulfonated blockcopolymers, albeit not the structures claimed in the present invention.The B blocks comprising a styrene block are described herein. In onepreferred embodiment, the saturated B blocks are unsubstituted styreneblocks, since the polymer will not then require a separate hydrogenationstep.

In addition, another aspect of the present invention is to include atleast one impact modifier block D having a glass transition temperatureless than 20° C. One such example of an impact modifier block Dcomprises a hydrogenated polymer or copolymer of a conjugated dieneselected from isoprene, 1,3-butadiene and mixtures thereof having avinyl content prior to hydrogenation of between 20 and 80 mol percentand a number average molecular weight of between 1,000 and 50,000.Another example would be an acrylate or silicone polymer having a numberaverage molecular weight of 1,000 to 50,000. In still another example,the D block would be a polymer of isobutylene having a number averagemolecular weight of 1,000 to 50,000.

Each A block independently has a number average molecular weight betweenabout 1,000 and about 60,000 and each B block independently has a numberaverage molecular weight between about 10,000 and about 300,000.Preferably each A block has a number average molecular weight of between2,000 and 50,000, more preferably between 3,000 and 40,000 and even morepreferably between 3,000 and 30,000. Preferably each B block has anumber average molecular weight of between 15,000 and 250,000, morepreferably between 20,000 and 200,000, and even more preferably between30,000 and 100,000. Note that the ranges can also include allcombinations of said number average molecular weights listed herewith.These molecular weights are most accurately determined by lightscattering measurements, and are expressed as number average molecularweight. Preferably, the sulfonated polymers have from about 8 molpercent to about 80 mol percent, preferably from about 10 to about 60mol percent A blocks, more preferably more than 15 mol percent A blocksand even more preferably from about 20 to about 50 mol percent A blocks.

The relative amount of vinyl aromatic monomers which are unsubstitutedstyrene monomer, ortho-substituted styrene monomer, meta-substitutedstyrene monomer, alpha-methylstyrene monomer, 1,1-diphenylethylenemonomer, and 1,2-diphenylethylene monomer in the sulfonated blockcopolymer is from about 5 to about 90 mol percent, preferably from about5 to about 85 mol percent. In alternative embodiments, the amount isfrom about 10 to about 80 mol percent, preferably from about 10 to about75 mol percent, more preferably from about 15 to about 75 mol percent,with the most preferred being from about 25 to about 70 mol percent.Note that the ranges can include all combinations of mol percents listedherewith.

As for the saturated B block, in one preferred embodiment the molpercent of vinyl aromatic monomers which are unsubstituted styrenemonomer, ortho-substituted styrene monomer, meta-substituted styrenemonomer, alpha-methylstyrene monomer, 1,1-diphenylethylene monomer, and1,2-diphenylethylene monomer in each B block is from about 10 to about100 mol percent, preferably from about 25 to about 100 mol percent, morepreferably from about 50 to about 100 mol percent, even more preferablyfrom about 75 to about 100 mol percent and most preferably 100 molpercent. Note that the ranges can include all combinations of molpercents listed herewith.

As for the level of sulfonation, typical levels are where each B blockcontains one or more sulfonic functional groups. Preferred levels ofsulfonation are 10 to 100 mol percent based on the mol percent of vinylaromatic monomers which are unsubstituted styrene monomer,ortho-substituted styrene monomer, meta-substituted styrene monomer,alpha-methylstyrene monomer, 1,1-diphenylethylene monomer, and1,2-diphenylethylene monomer in each B block, more preferably about 20to 95 mol percent and even more preferably about 30 to 90 mol percent.Note that the range of sulfonation can include all combinations of molpercents listed herewith. The level of sulfonation is determined bytitration of a dry polymer sample, which has been redissolved intetrahydrofuran with a standardized solution of NaOH in a mixed alcoholand water solvent.

2. Overall Anionic Process to Prepare Polymers

With regard to the process to prepare the polymers, the anionicpolymerization process comprises polymerizing the suitable monomers insolution with a lithium initiator. The solvent used as thepolymerization vehicle may be any hydrocarbon that does not react withthe living anionic chain end of the forming polymer, is easily handledin commercial polymerization units, and offers the appropriatesolubility characteristics for the product polymer. For example,non-polar aliphatic hydrocarbons, which are generally lacking inionizable hydrogen atoms make particularly suitable solvents. Frequentlyused are cyclic alkanes, such as cyclopentane, cyclohexane,cycloheptane, and cyclooctane, all of which are relatively non-polar.Other suitable solvents will be known to those skilled in the art andcan be selected to perform effectively in a given set of processconditions, with polymerization temperature being one of the majorfactors taken into consideration.

Starting materials for preparing the block copolymers of the presentinvention include the initial monomers noted above. Other importantstarting materials for anionic co polymerizations include one or morepolymerization initiators. In the present invention such include, forexample, alkyl lithium compounds such as s-butyllithium, n-butyllithium,t-butyllithium, amyllithium and the like and other organo lithiumcompounds including di-initiators such as the di-sec-butyl lithiumadduct of m-diisopropenyl benzene. Other such di-initiators aredisclosed in U.S. Pat. No. 6,492,469, each incorporated herein byreference. Of the various polymerization initiators, s-butyllithium ispreferred. The initiator can be used in the polymerization mixture(including monomers and solvent) in an amount calculated on the basis ofone initiator molecule per desired polymer chain. The lithium initiatorprocess is well known and is described in, for example, U.S. Pat. Nos.4,039,593 and Re. 27,145, which descriptions are incorporated herein byreference.

Polymerization conditions to prepare the block copolymers of the presentinvention are typically similar to those used for anionicpolymerizations in general. In the present invention polymerization ispreferably carried out at a temperature of from about −30° C. to about150° C., more preferably about 10° C. to about 100° C., and mostpreferably, in view of industrial limitations, from about 30° C. toabout 90° C. The polymerization is carried out in an inert atmosphere,preferably nitrogen, and may also be accomplished under pressure withinthe range of from about 0.5 to about 10 bars. This copolymerizationgenerally requires less than about 12 hours, and can be accomplished infrom about 5 minutes to about 5 hours, depending upon the temperature,the concentration of the monomer components, and the molecular weight ofthe polymer that is desired. When two or more of the monomers are usedin combination, any copolymerization form selected from random, block,tapered block, controlled distribution block, and the likecopolymerization forms may be utilized.

It is recognized that the anionic polymerization process could bemoderated by the addition of a Lewis acid, such as an aluminum alkyl, amagnesium alkyl, a zinc alkyl or combinations thereof. The affects ofthe added Lewis acid on the polymerization process are 1) to lower theviscosity of the living polymer solution allowing for a process thatoperates at higher polymer concentrations and thus uses less solvent, 2)to enhance the thermal stability of the living polymer chain end whichpermits polymerization at higher temperatures and again, reduces theviscosity of the polymer solution allowing for the use of less solvent,and 3) to slow the rate of reaction which permits polymerization athigher temperatures while using the same technology for removing theheat of reaction as had been used in the standard anionic polymerizationprocess. The processing benefits of using Lewis acids to moderateanionic polymerization techniques have been disclosed in U.S. Pat. Nos.6,391,981; 6,455,651; and 6,492,469, which are herein incorporated byreference. Related information is disclosed in U.S. Pat. Nos. 6,444,767and 6,686,423, each incorporated herein by reference. The polymer madeby such a moderated, anionic polymerization process can have the samestructure as one prepared using the conventional anionic polymerizationprocess and as such, this process can be useful in making the polymersof the present invention. For Lewis acid moderated, anionicpolymerization processes, reaction temperatures between 100° C. and 150°C. are preferred as at these temperatures it is possible to takeadvantage of conducting the reaction at very high polymerconcentrations. While a stoichiometric excess of the Lewis acid may beused, in most instances there is not sufficient benefit in improvedprocessing to justify the additional cost of the excess Lewis acid. Itis preferred to use from about 0.1 to about 1 mole of Lewis acid permole of living, anionic chain ends to achieve an improvement in processperformance with the moderated, anionic polymerization technique.

Preparation of Radial (Branched) Polymers Requires a Post-PolymerizationStep Called “coupling”. In the above radial formulas n is an integer offrom 2 to about 30, preferably from about 2 to about 15, and morepreferably from 2 to 6, and X is the remnant or residue of a couplingagent. A variety of coupling agents are known in the art and can be usedin preparing the coupled block copolymers of the present invention.These include, for example, dihaloalkanes, silicon halides, siloxanes,multifunctional epoxides, silica compounds, esters of monohydricalcohols with carboxylic acids, (e.g. methylbenzoate and dimethyladipate) and epoxidized oils. Star-shaped polymers are prepared withpolyalkenyl coupling agents as disclosed in, for example, U.S. Pat. Nos.3,985,830; 4,391,949; and 4,444,953; as well as Canadian Patent No.716,645, each incorporated herein by reference. Suitable polyalkenylcoupling agents include divinylbenzene, and preferably m-divinylbenzene.Preferred are tetra-alkoxysilanes such as tetra-methoxysilane (TMOS) andtetra-ethoxysilane (TEOS), tri-alkoxysilanes such asmethyltrimethoxysilane (MTMS), aliphatic diesters such as dimethyladipate and diethyl adipate, and diglycidyl aromatic epoxy compoundssuch as diglycidyl ethers deriving from the reaction of bis-phenol A andepichlorohydrin.

3. Process to Prepare Hydrogenated Block Copolymers.

As noted, in some cases—i.e., (1) when there is a diene in the Binterior blocks, (2) when the A block is a polymer of a 1,3-cyclodiene,(3) when there is an impact modifier block D and (4) when the A block isa polymer of a conjugated diene having a vinyl content of less than 35mol percent—it is necessary to selectively hydrogenate the blockcopolymer to remove any ethylenic unsaturation. Hydrogenation generallyimproves thermal stability, ultraviolet light stability, oxidativestability, and, therefore, weatherability of the final polymer, andreduces any chance for sulfonation of the A block or the D block.

Hydrogenation can be carried out via any of the several hydrogenation orselective hydrogenation processes known in the prior art. For example,such hydrogenation has been accomplished using methods such as thosetaught in, for example, U.S. Pat. Nos. 3,595,942, 3,634,549, 3,670,054,3,700,633, and Re. 27,145, the disclosures of which are incorporatedherein by reference. These methods operate to hydrogenate polymerscontaining ethylenic unsaturation and are based upon operation of asuitable catalyst. Such catalyst, or catalyst precursor, preferablycomprises a Group VIII metal such as nickel or cobalt which is combinedwith a suitable reducing agent such as an aluminum alkyl or hydride of ametal selected from Groups I-A, II-A and III-B of the Periodic Table ofthe Elements, particularly lithium, magnesium or aluminum. Thispreparation can be accomplished in a suitable solvent or diluent at atemperature from about 20° C. to about 80° C. Other catalysts that areuseful include titanium based catalyst systems.

Hydrogenation can be carried out under such conditions that at leastabout 90 percent of the conjugated diene double bonds have been reduced,and between zero and 10 percent of the arene double bonds have beenreduced. Preferred ranges are at least about 95 percent of theconjugated diene double bonds reduced, and more preferably about 98percent of the conjugated diene double bonds are reduced.

Once the hydrogenation is complete, it is preferable to oxidize andextract the catalyst by stiffing with the polymer solution a relativelylarge amount of aqueous acid (preferably 1 to 30 percent by weightacid), at a volume ratio of about 0.5 parts aqueous acid to 1 partpolymer solution. The nature of the acid is not critical. Suitable acidsinclude phosphoric acid, sulfuric acid and organic acids. This stirringis continued at about 50° C. for from about 30 to about 60 minutes whilesparging with a mixture of oxygen in nitrogen. Care must be exercised inthis step to avoid forming an explosive mixture of oxygen andhydrocarbons.

4. Process to Make Sulfonated Polymers

Once the polymer is polymerized, and if necessary, hydrogenated, it willbe sulfonated using a sulfonation agent, by processes known in the art,such as those taught in U.S. Pat. Nos. 3,577,357; 5,239,010 and5,516,831, each incorporated herein by reference. One process uses acylsulfates. Acyl sulfates are known in the art as described in“Sulfonation and Related Reactions”, E. E. Gilbert, Robert E. KriegerPublishing Co., Inc., Huntington, N.Y., pp 22, 23, and 33 (1977) (Firstedition published by John Wiley & Sons, Inc. (1965)). The preferredsulfonating reagent is “acetyl sulfate”.

The acetyl sulfate route of sulfonation is said to be one of the leastharsh and cleanest of the methods. In the acetyl sulfate route, theacetyl sulfate is made by combining concentrated sulfuric acid with amolar excess of acetic anhydride in a suitable solvent such as1,2-dichloroethane. This is either made prior to the reaction orgenerated “in situ” in the presence of the polymer. The reportedtemperature for the sulfonation ranges from 0° C. to 50° C. and thereaction time is typically on the order of 2 to 6 hours. The acetylsulfate is typically made fresh because it can react with itself overtime and at elevated reaction temperatures to form sulfoacetic acid(HSO3CH2COOH). Sulfonation using acetyl sulfate is often notquantitative, conversion of acetyl sulfate may be 50% to 60% for styreneblock copolymer sulfonation although broader ranges may be achieved.

Isolation of sulfonated polymers is often done by steam stripping or bycoagulation in boiling water. Once the sulfonation reaction iscompleted, the block copolymers can be cast directly into an articleform (e.g., membrane) without the necessity of isolating the blockcopolymer as in the previous step. The quantity of molecular unitscontaining sulfonic acid or sulfonate functional groups in the modifiedblock copolymer is dependent on the content and the aromatic structureof the alkenyl arene therein. Once these parameters are fixed, thenumber of such groups present is dependent on the degree offunctionality desired between a minimum and maximum degree offunctionality based on these parameters. The minimum degree offunctionality corresponds on the average to at least about one (1),preferably at least about three (3) sulfonic acid or sulfonate groupsper molecule of the block copolymer. It is presently believed that theaddition of about one (1) sulfonic acid or sulfonate group per non-parasubstituted aromatic group of the B blocks is limiting. Preferably, thefunctionality is between about 10 and 100% of the non-para substitutedaromatic groups in the B blocks, more preferably about 20 to about 90%of such groups, most preferably about 25 to about 75 mol percent.

Another route to sulfonate the polymers is the use of sulfur trioxide asdisclosed in U.S. Pat. No. 5,468,574, incorporated herein by reference.Other routes to sulfonate the polymers include (1) reaction with acomplex of sulfur trioxide and an ether, and (2) reaction with atriethylphosphate/sulfur trioxide adduct as disclosed in U.S. Pat. No.5,239,010, incorporated herein by reference. Similar techniques usingrelated phosphorous reagents, include reaction of sulfur trioxide withcomplexes of phosphorous pentoxide and tris(2-ethylhexyl)phosphate asdisclosed in PCT Publication WO 2005/030812 A1; this publication alsoincludes the disclosure of sulfuric acid, preferably using silversulfate as a catalyst, various chlorosulfonic acid agents, and mixturesof sulfur dioxide with chlorine gas for the sulfonation reaction.

5. Process to Neutralize Sulfonated Polymers

Another embodiment of the present invention is to “neutralize” themodified block copolymer with a base. This may be desirable wheneverimproved stability of the polymer or enhanced strength of the polymer atelevated temperatures is needed. Neutralization of the sulfonated blockcopolymer also tends to reduce the corrosive nature of the acidmoieties, enhances the driving force for phase separation in the blockcopolymer, improves resistance to hydrocarbon solvents, and in manyinstances improves recovery of the sulfonated polymer from thebyproducts of the sulfonation reaction.

The sulfonated block copolymer may be at least partly neutralizedwherein a portion of the sulfonic functional groups, proton donors orBronsted acids, have been neutralized with a base, a Bronsted or LewisBase. Using the definitions of Bronsted and Lewis bases as contained inChapter 8 and the references therein of Advanced Organic Chemistry,Reactions, Mechanisms, and Structures, Fourth Edition by Jerry March,John Wiley & Sons, New York, 1992, a base is a compound with anavailable pair of electrons. Optionally, the base could be polymeric ornon-polymeric. Illustrative embodiments of the group of non-polymericbases would include an ionizable metal compound which reacts with theBronsted acid centers in the sulfonated block copolymer to form metalsalts. In one embodiment, the ionizable metal compound comprises ahydroxide, an oxide, an alcoholate, a carboxylate, a formate, anacetate, a methoxide, an ethoxide, a nitrate, a carbonate or abicarbonate. Preferably the ionizable metal compound is a hydroxide, anacetate, or a methoxide, more preferably the ionizable metal compound isa hydroxide. Regarding the particular metal, it is preferred that theionizable metal compound comprises Na+, K+, Li+, Cs+, Ag+, Hg+, Cu+,Mg2+, Ca2+, Sr2+, Ba2+, Cu2+, Cd2+, Hg2+, Sn2+, Pb2+, Fe2+, Co2+, Ni2+,Zn2+, Al3+, Sc3+, Fe3+, La3+ or Y3+ compounds. Preferably the ionizablemetal compound is an Ca2+, Fe3+, or Zn2+ compound, such as zinc acetate,more preferably the ionizable metal compound is a Ca2+ compound.Alternatively, amines will react as bases with the acid centers in thesulfonated block copolymers of the present invention to form ammoniumions. Suitable non-polymeric amines would include primary, secondary,and tertiary amines and mixtures thereof wherein the substituents wouldbe linear, branched, or cyclic aliphatic or aromatic moieties ormixtures of the various types of substituents. Aliphatic amines wouldinclude ethylamine, diethylamine, triethylamine, trimethylamine,cyclohexylamine, and the like. Suitable aromatic amines would includepyridine, pyrrole, imidazole, and the like. Analogous polymeric amineswould include polyethyleneamine, polyvinylamine, polyallylamine,polyvinylpyridene, and the like. With regard to the level ofneutralization, it is preferred that the level be between 5 to 100 molpercent of the sulfonation sites, more preferably the level is between20 and 100 mol percent, even more preferably the level is between 50 to100 mol percent of the sulfonation sites. Such neutralization is taughtin U.S. Pat. Nos. 5,239,010 and 5,516,831, which disclosures are hereinincorporated by reference.

Other neutralization techniques include processes wherein a portion ofsaid sulfonic functional groups have been neutralized with aluminumacetylacetonate, such as taught in U.S. Pat. No. 6,653,408, and reactionwith an agent represented by the formula MRx, where M is a metal ion, Ris selected independently from the group consisting of hydrogen andhydrocarbyl groups and x is an integer from 1 to 4, such as taught inU.S. Pat. No. 5,003,012. The disclosures of U.S. Pat. Nos. 6,653,408 and5,003,012 are herein incorporated by reference.

In yet another embodiment, the sulfonated block copolymer is modified bya hydrogen bonding interaction with a base, a Bronsted or Lewis Base.Using the definitions of Bronsted and Lewis bases as contained inChapter 8 and the references therein of Advanced Organic Chemistry,Reactions, Mechanisms, and Structures, Fourth Edition by Jerry March,John Wiley & Sons, New York, 1992, a base is a compound with anavailable pair of electrons. In this case, the base is not sufficientlystrong to neutralize the Bronsted acid centers in the sulfonated blockcopolymer, but is strong enough to achieve a significant attraction tothe sulfonated block copolymer via a hydrogen bonding interaction. Asnoted above, nitrogen compounds often have an available electron pairand many interact with sulfonic acid centers via hydrogen bondingwithout effective neutralization of the acid species. Examples of suchnitrogen containing materials include nitriles, urethanes, and amides.Their polymeric analogs, polyacrylamide, polyacrylonitrile, nylons, ABS,and polyurethanes, could be used as modifying agents which interact withthe sulfonated block copolymer by hydrogen bonding interactions, aswell. In a similar way, oxygen containing compounds that have anavailable pair of electrons that will interact as bases with the acidcenters in sulfonated block copolymers forming various oxonium ions.Both polymeric and non-polymeric ethers, esters, and alcohols might beused in this way to modify a sulfonated block copolymer of the presentinvention. The sulfonated polymers of the present invention may bemodified by acid-base hydrogen bonding interactions when combined withglycols, to include polyethylene glycol, and polypropylene glycol, ormixtures of polyethylene glycol and polypropylene glycol alone or withother substituents (i.e., Pluronics® and Pepgel) and the like,polytetrahydrofuran, esters, to include polyethylene terephthalate,polybutyleneterephthalate, aliphatic polyesters, and the like, andalcohols to include polyvinylalcohol, poly saccharides, and starches.

Those of ordinary skill in the art will recognize that in certaininstances it might be desirable to further react the sulfonated blockcopolymer with other substituents such as one or more halogen groups(e.g., fluorine).

With regard to the ionizable metal compounds, it is believed thatincreased high temperature properties of these ionic copolymers are theresult of an ionic attraction between the metal ion and one or moreionized sulfonate functional groups in the B block domain. This ionicattraction results in the formation of ionic crosslinks, which occurs inthe solid state. The improvement in the mechanical properties anddeformation resistance resulting from the neutralization of the ionic Bblock domains is greatly influenced by the degree of neutralization and,therefore, the number of the ionic crosslinks and the nature of thecrosslink involved. Illustrative embodiments of non-polymeric basesinclude an ionizable metal compound which reacts to form metal salts.The ionizable metal compound comprises a hydroxide, an oxide, analcoholate, a carboxylate, a formate, an acetate, a methoxide, anethoxide, a nitrate, a carbonate or a bicarbonate.

Alternatively, amines can be reacted as bases with the acid centers inthe sulfonated block copolymers of the present invention to formammonium ions. Suitable non-polymeric amines include primary, secondary,and tertiary amines and mixtures thereof wherein the substituents wouldbe linear, branched, or cyclic aliphatic or aromatic moieties ormixtures of the various types of substituents. Aliphatic amines includeethylamine, diethylamine, triethylamine, trimethylamine,cyclohexylamine, and the like. Suitable aromatic amines includepyridine, pyrrole, imidazole, and the like. Analogous polymeric amineswould include polyethyleneamine, polyvinylamine, polyallylamine,polyvinylpyridene, and the like.

Examples of nitrogen containing materials include nitriles, urethanes,and amides, and their polymeric analogs, polyacrylamide,polyacrylonitrile, nylons, ABS, and polyurethanes. Suitable examples ofoxygen containing compounds include both polymeric and non-polymericethers, esters, and alcohols.

The degree of sulfonation and of neutralization may be measured byseveral techniques. For example, infrared analysis or elemental analysismay be employed to determine the overall degree of functionality.Additionally, the titration of a solution of the block copolymer with astrong base may be utilized to determine the degree of functionalityand/or the degree of neutralization (metal sulfonate salt content).Neutralization as used herein is based on the percentage of sulfonateions as compared to the total sulfonic acid and sulfonate groupfunctionality. Reaction conditions and processes are disclosed furtherin the examples and in U.S. Pat. Nos. 5,239,010 and 5,516,831, thedisclosures of which are herein incorporated by reference.

6. Isolation of Sulfonated Polymers

In one embodiment, the last step, following all polymerization(s) andsulfonation reactions as well as any desired post-treatment processes,is a finishing treatment to remove the final polymer from the solvent.Various means and methods are known to those skilled in the art, andinclude use of steam to evaporate the solvent, and coagulation of thepolymer followed by filtration. Coagulation with a non-solvent followedby filtration has been used to isolate the sulfonated polymers, as well.In instances where the spent reagents and byproducts are volatile,recovery in a fluidized bed drier could be used. Following any one ofthese finishing treatments in this embodiment, it is preferable to washthe resulting polymer one or more times in water in order to remove anyreagent residues that remain from the sulfonation process. When water isadded to the resulting polymer, a solid-in-liquid suspension having amilky white color is obtained. The polymer is removed from the opaquesuspension by either filtering the final product out of the suspensionor allowing the polymer to settle and then removing the aqueous phase.In an alternative embodiment, once the sulfonation reaction iscompleted, the block copolymers are cast directly into an article form(e.g., membrane) without the necessity of isolating the block copolymeras in the previous step. In this particular embodiment the article(e.g., membrane) can be submerged in water and will retain its form(solid) while in the water. In other words, the block copolymer will notdissolve in water or disperse in water.

Independent of the method of isolation, the final result is a “clean”block copolymer useful for a wide variety of challenging applications,according to the properties thereof.

7. Properties of Sulfonated Polymers

The polymers of the present invention, as a direct consequence of beingselectively sulfonated in the interior segment of one of the blockcopolymers mentioned above, e.g., an interior segment of a saturatedtriblock copolymer, have a unique balance of physical properties, whichrender them extraordinarily useful in a variety of applications. As theinventive sulfonated block copolymers are not crosslinked, thesecopolymers may be cast into membranes or coatings. In the castingprocess, the copolymers tend to self assemble into microphase separatedstructures. The sulfonate groups organize into a separate phase or ionchannels. When these channels form a continuous structure spanning thedistance between the two sides of the membrane they have a remarkableability to transport water and protons.

It is the integrity of the phase formed as a consequence of theseparation of the end segments, which provides the membrane withstrength. As the end segments have little or no sulfonate functionality,they are extremely resistant to being plasticized by the addition ofwater, as well as by methanol. It is this effect that allows thegeneration of membranes with good wet strength. The hardness andflexibility of the membrane can be easily adjusted in two ways. Thestyrene content of the interior segment (B block) of the precursor blockcopolymer can be increased from a low level to 100% wt. As the styrenecontent of the interior segment is increased, the product sulfonatedblock copolymer membrane will become harder and less flexible.Alternatively, the end segment (A block) content of the precursor blockcopolymer may be increased from about 10% wt to about 90% wt with theeffect that the resulting sulfonated block copolymer membrane willbecome harder and less flexible as the end block content of the polymeris increased. At lower end block contents, the membrane will be tooweak; at end block contents above about 90% wt, the product membraneswill have poor transport properties.

By adjusting the structure of the precursor block copolymer, sulfonatedpolymer membranes may be prepared having surprising wet strength, wellcontrolled and high rates of water and/or proton transport across themembrane, exceptional barrier properties for organic and non-polarliquids and gases, tunable flexibility and elasticity, controlledmodulus, and oxidative and thermal stability. It is expected that themembranes would have good resistance to methanol transport and goodretention of properties in the presence of methanol. As these membranesare not crosslinked, they can be reshaped or reprocessed by redissolvingthem in solvent and recasting the resulting solution; they may be reusedor reshaped using various polymer melt processes, also.

An interesting feature of these uniformly microphase separated materialsis that one phase readily absorbs water while the second phase is a muchless polar thermoplastic. Water in the sulfonated phase could be heatedusing any of a variety of indirect methods, exposure to microwave orradio frequency radiation, to name a couple; the water heated in thisway might transfer sufficient heat to the thermoplastic phase to allowsoftening or flow in this phase. Such a mechanism could be the basis forpolymer “welding” or molding operations that would not require directheating of the thermoplastic phase. Such a process could be veryefficient because it doesn't require heating the whole part, fastbecause intensity can be controlled over a wide range, and safe becauseonly the irradiated area will be hot resulting in lower overall parttemperature. Such a process would be well suited to the assembly ofarticles from pieces of fabric. Rather than stitching the piecestogether, they might be “welded” together—no stitching holes. It mightalso be used for electronic assemblies and building construction. In arelated concept, films (to include compounded adhesive films) preparedfrom polymers of the present invention could be applied as single useadhesives and subsequently removed by treatment with water.

As shown in the examples that follow, the block copolymers of thepresent invention have a number of significant and unexpectedproperties. For example, sulfonated block copolymers according to thepresent invention have a water permeability greater than 0.1 times 10-6,preferably greater than 1.0 times 10-6, grams per Pascal.meter.houraccording to ASTM E96-00 “desiccant” method, a wet tensile strengthgreater than 100 psi, preferably greater than 500 psi, according to ASTMD412, and a swellability of less than 100% by weight. In contrast, asshown in the examples, at sulfonation levels (presence of —SO3H units)above about 1.5 mmol/g polymer, the polymers of the prior art havelittle, if any, wet tensile strength. Whereas, the polymers of thepresent invention typically have wet tensile strengths above 500 psi,and in many cases about 1000 psi. Further, it has been shown thatpolymers of the present invention have a ratio of wet tensile strengthto dry tensile strength greater than 0.3.

8. End Uses, Compounds and Applications

The sulfonated block copolymers according to the present invention canbe used in a variety of applications and end uses. Such polymers havingselectively sulfonated interior blocks will find utility in applicationswhere the combination of good wet strength, good water and protontransport characteristics, good methanol resistance, easy film ormembrane formation, barrier properties, control of flexibility andelasticity, adjustable hardness, and thermal/oxidative stability areimportant. In one embodiment of the present invention, the inventivesulfonated block copolymers are used in electrochemical applications,such as in fuel cells (separator phase), proton exchange membranes forfuel cells, dispersions of metal impregnated carbon particles insulfonated polymer cement for use in electrode assemblies, includingthose for fuel cells, water electrolyzers (electrolyte), acid batteries(electrolyte separator), super capacitors (electrolyte), separation cell(electrolyte barrier) for metal recovery processes, sensors(particularly for sensing humidity) and the like. The inventivesulfonated block copolymers are also used as desalination membranes,coatings on porous membranes, absorbents, personal hygiene articles,water gels and as adhesives. Additionally, the inventive blockcopolymers are used in protective clothing and breathable fabricapplications where the membranes, coated fabrics, and fabric laminatescould provide a barrier of protection from various environmentalelements (wind, rain, snow, chemical agents, biological agents) whileoffering a level of comfort as a result of their ability to rapidlytransfer water from one side of the membrane or fabric to the other,e.g., allowing moisture from perspiration to escape from the surface ofthe skin of the wearer to the outside of the membrane or fabric and viceversa. Full enclosure suits made from such membranes and fabrics mightprotect first responders at the scene of an emergency where exposure tosmoke, a chemical spill, or various chemical or biological agents are apossibility. Similar needs arise in medical applications, particularlysurgery, where exposure to biological hazards is a risk. Surgical glovesand drapes fabricated from these types of membranes are otherapplications that could be useful in a medical environment. Articlesfabricated from these types of membranes could have antibacterial and/orantiviral and/or antimicrobial properties as reported in U.S. Pat. Nos.6,537,538, 6,239,182, 6,028,115, 6,932,619 and 5,925,621 where it isnoted that polystyrene sulfonates act as inhibitory agents against HIV(human immunodeficiency virus) and HSV (herpes simplex virus. Inpersonal hygiene applications, a membrane or fabric of the presentinvention that would transport water vapor from perspiration whileproviding a barrier to the escape of other bodily fluids and stillretain its strength properties in the wet environment would beadvantageous. The use of these types of materials in diapers and adultincontinence constructions would be improvements over existingtechnologies.

Fabrics can be made by either solution casting the sulfonated polymer ona liner fabric, or laminating a film of the sulfonated polymer between aliner fabric and a shell fabric.

The sulfonated block copolymers of the present invention can also beused in absorbent articles, and in particular with super absorbentmaterials. In particular, the sulfonated block copolymers could be usedto contain and/or distribute water to the super absorbent particles. Forexample, the super absorbent particles could be encased in a film of thesulfonated block copolymer. In other embodiments, the materials of thepresent invention will be resistant to bacterial build up. The use ofwater-swellable, generally water-insoluble absorbent materials, commonlyknown as super absorbents, in disposable absorbent personal careproducts is known. Such absorbent materials are generally employed inabsorbent products such as, for example, diapers, training pants, adultincontinence products, and feminine care products in order to increasethe absorbent capacity of such products, while reducing their overallbulk. Such absorbent materials are generally present as a composite ofsuper absorbent particles (SAP) mixed in a fibrous matrix, such as amatrix of wood pulp fluff. A matrix of wood pulp fluff generally has anabsorbent capacity of about 6 grams of liquid per gram of fluff. Thesuper absorbent materials (SAM) generally have an absorbent capacity ofat least about 10 grams of liquid per gram of SAM, desirably of at leastabout 20 grams of liquid per gram of SAM, and often up to about 40 gramsof liquid per gram of SAM.

In one embodiment of the present invention, the super absorbent materialcomprises a sodium salt of a cross-linked polyacrylic acid. Suitablesuper absorbent materials include, but are not limited to: DowAFA-177-140 and Drytech 2035 both available from Dow Chemical Company,Midland, Mich.; Favor SXM-880 available from Stockhausen, Inc. ofGreensboro, N.C.; Sanwet IM-632 available from Tomen America of NewYork, N.Y.; and Hysorb P-7050 available from BASF Corporation,Portsmouth, Va. Desirably, the absorbent composites of the presentinvention contain the above-described super absorbent materials incombination with the sulfonated block copolymers of the presentinvention, optionally containing a fibrous matrix containing one or moretypes of fibrous materials.

Applications such as coatings for portable water transport and storagedevices would take advantage of the combination of good mechanicalproperties of these polymers in wet environments with their tendency toresist the growth of biologically active species. This feature of blockcopolymers selectively sulfonated in the interior segment might beusefully applied to waste water (both sewage and industrial waste) pipeand treatment facilities. In a like manner, polymers of the presentinvention might be used to inhibit mold growth on the surfaces ofbuilding materials. These polymers may well inhibit the growth of largerorganisms as would be useful in avoiding fouling in various marineapplications. It is known to use the self-assembly feature ofselectively sulfonated block copolymers for the construction of humidityexchange cells as described in U.S. Pat. No. 6,841,601. In thisapplication, polymers of the present invention would allow thefabrication of membrane elements with good wet strength and would notrequire reinforcement. This could simplify the construction of membraneenergy recovery devices. Non-woven house wrap material, such as TYVEK®supplied by DuPont, are currently used in home construction to keep theelements of wind and weather from penetrating the exterior of the house.In some environments, this technology does not allow sufficienttransport of water vapor through the walls of the house with the resultthat conditions for the growth of mold develop in the walls of the home.An assembly prepared from polymers of the present invention mightprovide equally good barrier performance with the advantage of allowingeffective escape of water vapor from the walls of the house. In asimilar way, there is a need for a backing material for carpets thatallows the transport for water vapor. This need is critical in homesthat use concrete slab construction where water flow through theconcrete can be significant in periods of high humidity or excessiverain. If the carpet backing does not transport the water vapor at anequal rate, the build up of condensed water between the back of carpetand the surface of the slab can be problematic. Carpets backed with apolymer coating based upon polymers of the present invention couldovercome this problem.

The sulfonated polymers of the present invention may also be used asflame retardant materials—particularly for spraying a flammable articlein the path of an advancing fire. Such sulfonated polymers may be anexcellent “carrier” for conventional ignition retardant materials, whichtend not to be compatible with conventional hydrocarbon polymers.

Furthermore, the inventive sulfonated block copolymers can also be usedas a membrane to gather moisture from the environment. Accordingly, suchmembranes may be used to collect fresh water from the atmosphere in asituation where there is no ready supply of decent quality water.

Further, the copolymers of the present invention can be compounded withother components not adversely affecting the copolymer properties. Theblock copolymers of the present invention may be blended with a largevariety of other polymers, including olefin polymers, styrene polymers,tackifying resins, hydrophilic polymers and engineering thermoplasticresins, with polymer liquids such ionic liquids, natural oils,fragrances, and with fillers such as nanoclays, carbon nanotubes,fullerenes, and traditional fillers such as talcs, silica and the like.

In addition, the sulfonated polymers of the present invention may beblended with conventional styrene/diene and hydrogenated styrene/dieneblock copolymers, such as the styrene block copolymers available fromKraton Polymers LLC. These styrene block copolymers include linearS-B-S, S-I-S, S-EB-S, S-EP-S block copolymers. Also included are radialblock copolymers based on styrene along with isoprene and/or butadieneand selectively hydrogenated radial block copolymers.

Olefin polymers include, for example, ethylene homopolymers,ethylene/alpha-olefin copolymers, propylene homopolymers,propylene/alpha-olefin copolymers, high impact polypropylene, butylenehomopolymers, butylene/alpha olefin copolymers, and other alpha olefincopolymers or interpolymers. Representative polyolefins include, forexample, but are not limited to, substantially linear ethylene polymers,homogeneously branched linear ethylene polymers, heterogeneouslybranched linear ethylene polymers, including linear low densitypolyethylene (LLDPE), ultra or very low density polyethylene (ULDPE orVLDPE), medium density polyethylene (MDPE), high density polyethylene(HDPE) and high pressure low density polyethylene (LDPE). Other polymersincluded hereunder are ethylene/acrylic acid (EEA) copolymers,ethylene/methacrylic acid (EMAA) ionomers, ethylene/vinyl acetate (EVA)copolymers, ethylene/vinyl alcohol (EVOH) copolymers, ethylene/cyclicolefin copolymers, polypropylene homopolymers and copolymers,propylene/styrene copolymers, ethylene/propylene copolymers,polybutylene, ethylene carbon monoxide interpolymers (for example,ethylene/carbon monoxide (ECO) copolymer, ethylene/acrylic acid/carbonmonoxide terpolymer and the like). Still other polymers includedhereunder are polyvinyl chloride (PVC) and blends of PVC with othermaterials.

Styrene polymers include, for example, crystal polystyrene, high impactpolystyrene, medium impact polystyrene, styrene/acrylonitrilecopolymers, styrene/acrylonitrile/butadiene (ABS) polymers, syndiotacticpolystyrene, sulfonated polystyrene and styrene/olefin copolymers.Representative styrene/olefin copolymers are substantially randomethylene/styrene copolymers, preferably containing at least 20, morepreferably equal to or greater than 25 weight percent copolymerizedstyrene monomer.

For the purposes of the specification and claims, the term “engineeringthermoplastic resin” encompasses the various polymers such as forexample thermoplastic polyester, thermoplastic polyurethane, poly(arylether) and poly(aryl sulfone), polycarbonate, acetal resin, polyamide,halogenated thermoplastic, nitrile barrier resin, poly(methylmethacrylate) and cyclic olefin copolymers, and further defined in U.S.Pat. No. 4,107,131, the disclosure of which is hereby incorporated byreference.

Tackifying resins include polystyrene block compatible resins andmidblock compatible resins. The polystyrene block compatible resin maybe selected from the group of coumarone-indene resin, polyindene resin,poly(methyl indene) resin, polystyrene resin,vinyltoluene-alphamethylstyrene resin, alphamethylstyrene resin andpolyphenylene ether, in particular poly(2,6-dimethyl-1,4-phenyleneether). Such resins are e.g. sold under the trademarks “HERCURES”,“ENDEX”, “KRISTALEX”, “NEVCHEM” and “PICCOTEX”. Resins compatible withthe hydrogenated (interior) block may be selected from the groupconsisting of compatible C5 hydrocarbon resins, hydrogenated C5hydrocarbon resins, styrenated C5 resins, C5/C9 resins, styrenatedterpene resins, fully hydrogenated or partially hydrogenated C9hydrocarbon resins, rosins esters, rosins derivatives and mixturesthereof. These resins are e.g. sold under the trademarks “REGALITE”,“REGALREZ”, “ESCOREZ” and “ARKON.

Hydrophilic polymers include polymeric bases which are characterized ashaving an available pair of electrons. Examples of such bases includepolymeric amines such as polyethyleneamine, polyvinylamine,polyallylamine, polyvinylpyridene, and the like; polymeric analogs ofnitrogen containing materials such as polyacrylamide, polyacrylonitrile,nylons, ABS, polyurethanes and the like; polymeric analogs of oxygencontaining compounds such as polymeric ethers, esters, and alcohols; andacid-base hydrogen bonding interactions when combined with glycols suchas polyethylene glycol, and polypropylene glycol, and the like,polytetrahydrofuran, esters (including polyethylene terephthalate,polybutyleneterephthalate, aliphatic polyesters, and the like), andalcohols (including polyvinylalcohol), poly saccharides, and starches.Other hydrophilic polymers that may be utilized include sulfonatedpolystyrene. Hydrophilic liquids such as ionic liquids may be combinedwith the polymers of the present invention to form swollen conductivefilms or gels. Ionic liquids such as those described in U.S. Pat. Nos.5,827,602 and 6,531,241 (which disclosures are herein incorporated byreference) could be introduced into the sulfonated polymers either byswelling a previously cast membrane, or by adding to the solvent systembefore casting a membrane, film coating or fiber. Such a combinationmight find usefulness as a solid electrolyte or water permeablemembrane.

Exemplary materials that could be used as additional components wouldinclude, without limitation:

-   1) pigments, antioxidants, stabilizers, surfactants, waxes, and flow    promoters;-   2) particulates, fillers and oils; and-   3) solvents and other materials added to enhance processability and    handling of the composition.

With regard to the pigments, antioxidants, stabilizers, surfactants,waxes and flow promoters, these components, when utilized incompositions with the sulfonated block copolymers of the presentinvention may be included in amounts up to and including 10%, i.e., from0 to 10%, based on the total weight of the composition. When any one ormore of these components are present, they may be present in an amountfrom about 0.001 to about 5%, and even more preferably from about 0.001to about 1%.

With regard to particulates, fillers and oils, such components may bepresent in an amount up to and including 50%, from 0 to 50%, based onthe total weight of the composition. When any one or more of thesecomponents are present, they may be present in an amount from about 5 toabout 50%, preferably from about 7 to about 50%.

Those of ordinary skill in the art will recognize that the amount ofsolvents and other materials added to enhance processability andhandling of the composition will in many cases depend upon theparticular composition formulated as well as the solvent and/or othermaterial added. Typically such amount will not exceed 50%, based on thetotal weight of the composition.

The sulfonated block copolymers of the present invention can be used tomake any of the articles noted above and in many instances will take anynumber of forms such as in the form of a film, sheet, coating, band,strip, profile, molding, foam, tape, fabric, thread, filament, ribbon,fiber, plurality of fibers or, fibrous web. Such articles can be formedby a variety of processes such as for example casting, injectionmolding, over molding, dipping, extrusion (when the block copolymer isin neutralized form), roto molding, slush molding, fiber spinning (suchas electrospinning when the block copolymer is in neutralized form),film making, painting or foaming.

Applicants further claim a method of varying the transport properties ofa film cast out of the block copolymers of the present invention. Byusing a solvent mixture that comprises two or more solvents selectedfrom polar solvents and non-polar solvents, it is possible to obtaindifferent structures which demonstrate different mechanisms of storingwater. This in turn allows for the use of the block copolymers of thepresent invention to fine tune transport properties for particular usesutilizing a single class of block copolymers, i.e., the block copolymersof the present invention. Preferably, the polar solvents utilized in themethod of the present invention are selected from water, alcohols havingfrom 1 to 20 carbon atoms, preferably from 1 to 8 carbon atoms, morepreferably from 1 to 4 carbon atoms; ethers having from 1 to 20 carbonatoms, preferably from 1 to 8 carbon atoms, more preferably from 1 to 4carbon atoms, including cyclic ethers; esters of carboxylic acids,esters of sulfuric acid, amides, carboxylic acids, anhydrides,sulfoxides, nitriles, and ketones having from 1 to 20 carbon atoms,preferably from 1 to 8 carbon atoms, more preferably from 1 to 4 carbonatoms, including cyclic ketones. More specifically, the polar solventsare selected from methanol, ethanol, propanol, isopropanol, dimethylether, diethyl ether, dipropyl ether, dibutyl ether, substituted andunsubstituted furans, oxetane, dimethyl ketone, diethyl ketone, methylethyl ketone, substituted and unsubstituted tetrahydrofuran, methylacetate, ethyl acetate, propyl acetate, methylsulfate, dimethylsulfate,carbon disulfide, formic acid, acetic acid, sulfoacetic acid, aceticanhydride, acetone, cresol, creosol, dimethylsulfoxide (DMSO),cyclohexanone, dimethyl acetamide, dimethyl formamide, acetonitrile,water and dioxane, with water, tetrahydrofuran, methanol, ethanol,acetic acid, sulfoacetic acid, methylsulfate, dimethylsulfate, and IPAbeing the more preferred of the polar solvents.

Preferably the non-polar solvents utilized in the method of the presentinvention are selected from toluene, benzene, xylene, mesitylene,hexanes, heptanes, octanes, cyclohexane, chloroform, dichloroethane,dichloromethane, carbon tetrachloride, triethylbenzene,methylcyclohexane, isopentane, and cyclopentane, with toluene,cyclohexane, methylcyclohexane, cyclopentane, hexanes, heptanes,isopentane, and dichloroethane being the most preferred non-polarsolvents. As noted, the method utilizes two or more solvents.

This means that two, three, four or more solvents selected from polarsolvents alone, non-polar solvents alone or a combination of polarsolvents and non-polar solvents may be used. The ratio of the solventsto one another can vary widely. For examples, in solvent mixtures havingtwo solvents, the ratio can range from 99.99:0.01 to 0.01:99.9. Theconditions under which the films are cast can vary. Preferably, thefilms will be cast in air, at a temperature from 10° C. to 200° C.,preferably room temperature and onto the surface from which the film canbe released easily. Alternately the cast solution may be contacted witha non-solvent for the polymer, thereby removing the solvent and formingthe solid film or article. Alternately a coated fabric may be preparedby passing the woven or non-woven fabric through a solution of thepolymer. The solvent can then be removed by drying or by extractionusing a non-solvent for the polymer.

The following examples are intended to be illustrative only, and are notintended to be, nor should they be construed as limiting in any way ofthe scope of the present invention

Illustrative Embodiment #1

As polystyrene is selectively sulfonated in the para position, theinventors surmised that a polystyrene which had an alkyl group blockingthe para position would be less susceptible to sulfonation; it wouldtend to be slower to sulfonate or even completely resistant tosulfonation. In order to test this hypothesis, an experiment wasconducted on a 50/50 (w/w) mixture of polystyrene (48,200 Mn) andpoly(para-tert-butylstyrene) of about 22,000 Mn. The mixture wassulfonated, targeting 30 mol % of the polystyrene segments forsulfonation. The whole sulfonation reaction mixture was directly passedthrough alumina twice in order to remove the sulfonated polymericmaterial. The unabsorbed polymer solution was then dried and theresultant beige colored polymer was extracted with methanol to removesulfonating reagents. The polymer was dried again under vacuum. Thesulfonated, unabsorbed mixture and the original unreacted mixture wereanalyzed by quantitative 13C NMR and 1H NMR to determine the amount ofstyrene and para-tert-butylstyrene present (Table 1).

TABLE 1 NMR analysis of eluate for unreacted polymer. PolystyrenePoly-p-t- Polymer Sample Content butylstyrene Method of Preparation (wt%) (wt %) Analysis 50/50 mix before 49.3 50.7 ¹H NMR sulfonation 50/50mix after 6.2 93.8 ¹H NMR sulfonation and chromatography 50/50 mix after7.0 93.0 ¹³C NMR sulfonation and chromatography

Clearly, the sulfonation reaction favors the polystyrene residues overthe poly-para-tert-butylstyrene residues. Accordingly, polymer blocks ofpara-tert-butyl styrene are resistant to sulfonation and polymer blocksof unsubstituted styrene are susceptible to sulfonation.

Illustrative Embodiment #2

In this example, we have characterized various polymers prior tosulfonation. The block copolymers used in the sulfonation examples aredescribed below in Table #2.

TABLE 2 Base Polymers Interior Total block ptBS Apparent MW_(s) M_(n)(true) Polymer PSC PSC Content 2-arm 2-arm ID Polymer Type (% wt) (% wt)(% wt) (kg/mol) (kg/mol) COMPARATIVE EXAMPLES Aldrich-1 S-E/B-S 29 0 0106 71 G-1 S-E/B-S 30 0 0 80 54 G-2 S-E/B-S 30 0 0 112 71 A-1 S-S/E/B-S38 25 0 147 105 A-2 S-S/E/B-S 66 50 0 233 197 A-3 S-S/E/B-S 64 49 0 136107 INVENTIVE EXAMPLES T-1 (ptBS-S/E/B)_(n) 31 50 42 167 188 T-2(ptBS-S/E/B)_(n) 40 50 22 132 126 T-2.1 (ptBS-S/E/B)_(n) 22 36 47 102100 T-3 (ptBS/S-S/E/B)_(n) 42 50 22 145 137 T-4 (ptBS-S)_(n) 67 100 33142 170 T-5 (ptBS-S)_(n) 68 100 32 174 212 P-1 (pMS-S)_(n) 67 100 0 124132 E-1 (PE-S)_(n) 67 100 0 180 153 TS-1 (ptBS-E/B-S)_(n) 34 63 34 96 85TS-2 (ptBS-E/B-S)_(n) 42 73 43 67 75 TS-3 (ptBS-E/B-S)_(n) 35 60 36 9179 TS-4 (ptBS-E/B-S)_(n) 41 70 45 61 68 Where S = styrene, E = ethylene,B = butylene, ptBS = para-tert-butylstyrene, E/B is hydrogenatedpolybutadiene, pMS = p-methylstyrene and PE = hydrogenated low vinylcontent (around 10% 1,2-addition) polybutadiene, for (ptBS-E/B-S)xpolymers E/B-S was considered the interior block for the purpose ofcalculating the “Interior block PSC (%), “Apparent MWs 2-arm (kg/mol)”is the molecular weight of the linear triblock component (2-arm forcoupled polymers) of the product mixture as measured by GPC (calibratedwith polystyrene), “Mn(true) 2-arm (kg/mol)” is the Apparent MW valuewhich has been adjusted to estimate the actual MW of the triblockcopolymer using the following factors (adjusted based upon the MW of themonomer) to adjust the polystyrene equivalent molecular weight to trueMW values: for polystyrene, multiply the apparent MW by wt % polystyrenetimes 1.0, for hydrogenated polybutadiene (E/B), multiply the apparentMW by % wt hydrogenated polybutadiene times 0.54, for ptBS, multiply theapparent MW by wt % poly-para-tert-butylstyrene times 1.6, and for pMS,multiply the apparent MW by % wt para-methylstyrene times 1.2.“Aldrich-1” was used as purchased from Aldrich Chemical Company (Productnumber 448885).

The information provided with the Aldrich-1 sample indicated that it wasa sulfonated, selectively hydrogenated S-B-S triblock copolymer. Thepolymers noted G-1 and G-2 are selectively hydrogenated, S-B-S, triblockcopolymers available from KRATON Polymers. Polymers labeled A-1, A-2 andA-3 are selectively hydrogenated ABA triblock copolymers where the Ablocks are styrene polymer blocks and the B block prior to hydrogenationis a controlled distribution block copolymer of styrene and butadiene,manufactured according to the process disclosed in U.S. Published PatentApplication No. 2003/0176582. Hydrogenation using the proceduredescribed in the above noted Published Patent Application affordedPolymers A-1, A-2 and A-3.

Polymers labeled T-1, T-2 and T-2.1 are selectively hydrogenated (A-B)nXblock copolymers where the A block is a polymer block ofpara-tert-butylstyrene which was found to be resistant to sulfonationand the B block is an hydrogenated controlled distribution block ofbutadiene and styrene which was found to be susceptible to sulfonation.These three polymers were prepared using essentially the same processbut slightly different quantities of the various monomers. The A blockwas prepared by anionic polymerization of p-t-butylstyrene (ptBS) incyclohexane (about 40° C.) using s-BuLi as the initiator. The livingpoly-p-t-butylstyrene in cyclohexane solution was combined with thedistribution control agent (diethyl ether (DEE), 6% wt). Using theprocedure described in U.S. Published Patent Application No.2003/0176582, a controlled distribution of styrene in butadiene polymersegment was polymerized onto the poly-p-t-butylstyrene end segment. Theresulting diblock copolymer was coupled using methyl trimethoxysilane(Si/Li=0.45/1 (mol/mol)). The coupled polymer was a mostly linear A-B-Atriblock copolymer. Hydrogenation using a standard Co2+/triethylaluminummethod afforded the polymers described in Table 2.

The polymer labeled T-3 is similar to T-2, except that the A block is arandom copolymer block of unsubstituted styrene and p-t-butyl styrene.This polymer was prepared by a similar process with the exception that amixture of p-t-butylstyrene and styrene (90/10 (wt/wt)) was used in theanionic polymerization of the A block copolymer. The remainder of thesynthesis was as described for the preparation of T-2. Again a mostlylinear polymer triblock copolymer was obtained. As over 97% of theunsubstituted styrene monomer was in the B block of the copolymer, the Ablocks were resistant to sulfonation and the B blocks were sulfonationsusceptible.

The polymers labeled T-4 and T-5 are unhydrogenated block copolymers(A-B)nX where the A block is a polymer block of para-tert-butyl styreneand the B block is a polymer block of unsubstituted styrene. In thepreparation of T-4 and T-5, anionic polymerization of p-t-butylstyrenein cyclohexane was initiated using s-BuLi affording an A block having anestimated molecular weight of about 26,000 g/mol. The solution of livingpoly-p-t-butylstyrene in cyclohexane was treated with styrene monomer.The ensuing polymerization gave a living diblock copolymer having a Bblock composed only of polystyrene. The living polymer solution wascoupled using tetramethoxysilane (Si/Li=0.40/1 (mol/mol)). A mixture ofbranched (major component) and linear coupled polymers was obtained. Asthe interior segments of these polymers contained only polystyrene andthe end segments contained only poly-p-t-butylstyrene, the interiorsegments of these polymers were much more susceptible to sulfonationthan were the end segments.

The polymer labeled P-1 is an unhydrogenated block copolymer (A-B)nXblock copolymer where the A block is a polymer block ofpara-methylstyrene and the B block is a polymer block of unsubstitutedstyrene. In the preparation of P-1, anionic polymerization ofp-methylstyrene (used as received from Deltech) in cyclohexane wasinitiated using s-BuLi. Polymerization was controlled over thetemperature range of 30° C. to 65° C. affording an A block having a MW(styrene equivalent) of 20,100. The solution of livingpoly-p-methylstyrene in cyclohexane was treated with styrene monomer(50° C.). The ensuing polymerization gave a living diblock copolymer(styrene equivalent MW=60,200) having a B block composed only ofpolystyrene. The living polymer solution was coupled usingtetramethoxysilane (Si/Li=0.53/1 (mol/mol)). A mixture of branched(minor component) and linear coupled polymers was obtained. As theinterior segments of these polymers contained only polystyrene and theend segments contained only poly-p-methylstyrene, one would expect thatthe interior segments of these polymers would be much more susceptibleto sulfonation than were the end segments.

The polymer labeled E-1 is a selectively hydrogenated (A-B)nX blockcopolymer where the A block is a semi crystalline, polyethylene-likeblock of hydrogenated, low in vinyl content, polybutadiene which wasfound to be resistant to sulfonation and the B block is polystyrenewhich was found to be susceptible to sulfonation. The A block wasprepared by anionic polymerization of 1,3-butadiene in cyclohexane overa temperature range from 30° C. to 60° C. using s-BuLi as the initiator.The polymerization took a little over an hour to go to completion. Analiquot of the living polymer solution was quenched by the addition ofMeOH and analyzed using a H-NMR technique. Only 9% of the butadiene hadpolymerized by 1,2-addition (vinyl addition). The living, low in vinylcontent, polybutadiene in cyclohexane solution was reacted with styrene(50° C., about half an hour) to prepare the B block. The resulting,living diblock copolymer was coupled using tetramethoxysilane(Si/Li=0.52/1 (mol/mol)). The coupling reaction was allowed to proceedovernight at 70° C. The coupled polymer was a mostly linear A-B-Atriblock copolymer. Hydrogenation (70° C., 650 psig, about 2 hr) using astandard Co2+/triethylaluminum (30 ppm Co) method afforded the polymerdescribed in Table 2. An aliquot of the polymer solution was dried toremove the solvent. The dry polymer was easily compression molded at200° C. (well above the melting point of the semi-crystalline A blocks)into a thin film; this was a demonstration of the thermoplastic natureof the block copolymer.

The polymer labeled TS-1 is a selectively hydrogenated (A-D-B)nX blockcopolymer where the A block is a polymer block of para-tert-butylstyrene and the B block is a polymer block of unsubstituted styrene. Theblock labeled D is hydrogenated butadiene and X is a silicon containingresidue of the coupling agent. In the preparation of TS-1, anionicpolymerization of p-t-butylstyrene in cyclohexane was initiated usings-BuLi affording an A block having an estimated molecular weight ofabout 22,000 g/mol. Diethyl ether (6% wt of the total solution) wasadded to the solution of living poly-p-t-butylstyrene (ptBS-Li) incyclohexane. The ether-modified solution was treated with sufficientbutadiene to afford a second segment with a molecular weight of 28,000g/mol (ptBS-Bd-Li). The polybutadiene segment had a 1,2-addition contentof 40% wt. The living (ptBS-Bd-Li) diblock copolymer solution wastreated with styrene monomer. The ensuing polymerization gave a livingtriblock copolymer (ptBS-Bd-S-Li) having a third block composed only ofpolystyrene (S block MW=25,000 g/mol). The living polymer solution wascoupled using tetramethoxysilane (Si/Li=0.41/1 (mol/mol)). A mixture ofbranched, ((ptBS-Bd-S)3) (major component) and linear ((ptBS-Bd-S)2)coupled polymers was obtained. Hydrogenation using the method describedabove for T-1 and T-2 removed the C═C unsaturation in the butadieneportion of the pentablock copolymer affording the desired (A-D-B)nXblock copolymer. As the interior segment of this polymers contained onlypolystyrene and the end segments contained only poly-p-t-butylstyrene,the interior segments of these polymers were much more susceptible tosulfonation than were the end segments. The hydrogenated Bd segment, anE/B copolymer, was sulfonation resistant and acted as a tougheningspacer block between the poly-p-t-butylstyrene end segments and thesulfonated polystyrene center segment. Polymers TS-2, TS-3, and TS-4were prepared using the methods described above for the preparation ofpolymer TS-1 but used differing amounts of the monomers to afford thematerials described in Table 2.

Illustrative Embodiment #3

The polymers described in Illustrative Embodiment #2 were sulfonatedaccording to the procedure of the present invention.

In a representative experiment, an elastomeric triblock copolymer,polymer labeled T-2 from Table 2, having sulfonation resistant endsegments and a sulfonation susceptible interior segment was treated withacetylsulfate, a sulfonation agent. The triblock copolymer havingpoly-t-butylstyrene (ptBS) end segments and a interior segmentsynthesized by selective hydrogenation of a butadiene (Bd) and styrene(S) copolymer (S/E/B) having a controlled distribution of the twomonomers, ptBS-S/E/B-ptBS (20 g), was dissolved in 1,2-dichloroethane(DCE) (400 ml) and the solution heated to 43 C. The acetylsulfatereagent was prepared in a separate vessel by combining a cold (ice bath)solution of acetic anhydride (AcOAc) (10.85 g, 0.106 mol) in DCE (40 ml)with cold sulfuric acid (6.52 g, 0.067 mol). The cold solution ofacetylsulfate was added with stiffing to the polymer in DCE. Sulfonationconditions were maintained for 4.5 hr. The triblock copolymer, which hadbeen selectively sulfonated in the interior segment, was isolated fromboiling water, washed with an excess of water (until the wash water wasneutral in pH), and dried under vacuum. An aliquot of the dry,selectively sulfonated polymer (2.34 g) was dissolved in a mixture oftetrahydrofuran (THF) and methanol (MeOH) (5/1 (v/v)) and the polymerbound sulfonic acid functionality was titrated to a thymol blue endpointusing a solution of sodium hydroxide (NaOH) (0.245 N) in methanol/water(80/20 (w/w)). This analysis found that 33.6 mol % of the polystyrenesites in the block copolymer had been sulfonated.

In Table 3, polymers labeled T-1, T-3, TS-1, TS-2, TS-3 and TS-4 weresulfonated using essentially the same technique. The quantities ofreagents used in the subsequent experiments were slightly differentwhich resulted in slightly different levels of sulfonation (mmol ofsulfonate/g of polymer).

In a related experiment, a plastic triblock copolymer having sulfonationresistant end segments and a sulfonation susceptible interior segmentwas sulfonated with acetylsulfate. A triblock copolymer havingpoly-p-t-butylstyrene (ptBS) end segments and a polystyrene (S) interiorsegment, ptBS-S-ptBS (labeled polymer T-4.1, Table 2) (20 g), wasdissolved in 1,2-dichloroethane (DCE) (500 g) and the solution heated to49 C. The acetylsulfate reagent was prepared in a separate vessel bycombining a cold (ice bath) solution of acetic anhydride (AcOAc) (18 g,0.18 mol) in DCE (20-30 ml) with sulfuric acid (10.4 g, 0.11 mol). Thecold solution of acetylsulfate was added with stiffing to the polymer inDCE solution. Sulfonation conditions were maintained for 4.1 hr. Thetriblock copolymer, which had been selectively sulfonated in theinterior segment, was isolated by coagulation in an excess of water,washed with water to remove acidic residues which were not bound to thepolymer (until the wash water was neutral in pH), and dried undervacuum. An aliquot of the dry, selectively sulfonated polymer (1.04 g)was dissolved in a mixture of toluene and methanol (MeOH) (1/2 (v/v))and the polymer bound sulfonic acid functionality was titrated to athymol blue endpoint using a solution of sodium hydroxide (NaOH) (0.10N) in methanol/water (80/20 (w/w)). This analysis found that 37 mol % ofthe polystyrene sites in the interior block of the copolymer had beensulfonated.

This procedure was repeated several times using somewhat differentamounts of the sulfonating reagent affording the data reported in Table3.

In a closely related experiment, a plastic triblock copolymer havingpoly-p-methylstyrene (pMS) end segments and a polystyrene (S) interiorsegment, pMS-S-pMS (labeled polymer P-1, Table 2) (20 g), was dissolvedin 1,2-dichloroethane (DCE) (511 g) and the solution heated to 55 C. Theacetylsulfate reagent was prepared in a separate vessel by combining asolution of acetic anhydride (AcOAc) (20 g, 0.20 mol) in DCE (10 g) withcold sulfuric acid (12.2 g, 0.12 mol). The cold solution ofacetylsulfate was added with stiffing to the polymer in DCE solution.Sulfonation conditions were maintained for 4 hr. The triblock copolymer,which had been selectively sulfonated in the interior segment, wasisolated by coagulation in an excess of water, washed with water toremove acidic residues which were not bound to the polymer (until thewash water was neutral in pH), and dried under vacuum. An aliquot of thedry, selectively sulfonated polymer (1.0 g) was dissolved in a mixtureof tetrahydrofuran and MeOH (2/1 (v/v)) and the polymer bound sulfonicacid functionality was titrated to a thymol blue endpoint using asolution of sodium hydroxide (NaOH) (0.135 N) in methanol/water (80/20(w/w)). One would expect that about 35 mol % of the polystyrene sites inthe interior block of the copolymer would have been sulfonated.

A plastic triblock copolymer having polyethylene-like (hydrogenated, lowin vinyl content polybutadiene) end segments and a polystyrene (S)interior segment, PE-S-PE (labeled polymer E-1, Table 2) (20 g), wasdispersed in 1,2-dichloroethane (DCE) (500 g) and the solution heated to65 C. The acetyl sulfate reagent was prepared in a separate vessel bycombining a solution of cold acetic anhydride (AcOAc) (20 g, 0.19 mol)in DCE (20 ml) with sulfuric acid (12.6 g, 0.13 mol). The cold solutionof acetyl sulfate was added with stiffing to the polymer in DCE slurry.Sulfonation conditions were maintained for 4 hr. The triblock copolymer,which had been selectively sulfonated in the interior segment, wasisolated by decanting off the spent sulfonation reagent and the DCE,washed with water to remove acidic residues, which were not bound to thepolymer (until the wash water was neutral in pH), and dried undervacuum. An aliquot of the dry, selectively sulfonated polymer was heatedin the presence of xylene but did not dissolve. This was taken assupporting evidence that the polystyrene sites in the interior block ofthe copolymer had been sulfonated. In a like manner, the polymer couldno longer be compression molded as a consequence of the stronginteractions of the —SO3H sites present in the B block of the copolymer.

TABLE 3 Analysis of Sulfonated Polymers Sulfonation Level —SO₃H/StyrenePolymer —SO₃H/polymer (mol % basis styrene ID Polymer Type (mmol/g)content of polymer) COMPARATIVE EXAMPLES Aldrich-1 S-E/B-S 1.3 to 1.6 45to 55 G-1 S-E/B-S 0.9 30 G-2 S-E/B-S 0.80 27 A-1 S-S/E/B-S 0.6 17 A-1.1S-S/E/B-S 1.1 31 A-2 S-S/E/B-S 1.6 25 A-2 S-S/E/B-S 1.9 29 A-3 S-S/E/B-S2.3 38 INVENTIVE EXAMPLES T-1 (ptBS-S/E/B)_(n) 1.0 35 T-2(ptBS-S/E/B)_(n) 1.3 34 T-2.1 (ptBS-S/E/B)_(n) 1.5 47 T-2.1(ptBS-S/E/B)_(n) 1.0 32 T-2.1 (ptBS-S/E/B)_(n) 1.5 47 T-2.1(ptBS-S/E/B)_(n) 1.4 46 T-3 (ptBS/S-S/E/B)_(n) 1.2 28 T-4 (ptBS-S)_(n)0.7 9 T-4.1 (ptBS-S)_(n) 2.8 37 T-4 (ptBS-S)_(n) 2.0 27 T-4 (ptBS-S)_(n)2.0 27 T-4 (ptBS-S)_(n) 2.3 31 T-5 (ptBS-S)_(n) 2.4 37 T-5 (ptBS-S)_(n)1.8 27 T-5 (ptBS-S)_(n) 3.2 50 T-5 (ptBS-S)_(n) 1.5 23.8 TS-1(ptBS-E/B-S)_(n) 1.5 47 TS-1.1 (ptBS-E/B-S)_(n) 1.8 58 TS-2(ptBS-E/B-S)_(n) 2.5 64 TS-2.1 (ptBS-E/B-S)_(n) 1.8 46 P-1 (pMS-S)_(n)2.2 35 E-1 (PE-S)_(n) NA NA Where S = styrene, E = ethylene, B =butylene, ptBS = para-tert-butylstyrene and E/B is hydrogenatedpolybutadiene, the starting polymers are described in Table 2.“Aldrich-1” was used as purchased from Aldrich Chemical Company (Productnumber 448885); functionality as defined in MSDS. “NA” means notanalyzed.

Using the sulfonation technique described above, a wide range ofpolymers has been selectively sulfonated in the interior segment of theA-B-A block copolymers. Sulfonation levels have ranged from about 0.6 toabout 2.8 mmol of sulfonate functionality per gram of polymer forpolymers of the present invention (Polymers T-1, T-2, T-3, T-4, andP-1). The comparative example polymers which have been sulfonated in theend blocks (Aldrich-1 and G-1 which have styrene groups only in the Ablocks) or indiscriminately sulfonated over all of the blocks of thecopolymer (Polymers A-1 and A-2 which have reactive styrene groups inboth the A and the B blocks), using the sulfonation technique describedabove, had functionality levels distributed over this same range. All ofthese polymers were carried forward in the synthesis of membranes.

Illustrative Embodiment #4

The sulfonated block copolymers were cast in air, at room temperature,from solvent (mixtures contained varying amounts of tetrahydrofuran(THF), methanol (MeOH), and toluene (MeBz), the ratios being adjusted tosuit the solubility properties of the sulfonated block copolymers) ontothe surface of Teflon coated foil. The resulting films were tested ascast (data labeled “Dry”). Test specimens were stamped from thesemembranes using a Mini-D die. Tensile testing was according to ASTMD412. The reported data represent averages of results of 3 to 5 testedsamples depending on the variability of the sample results and amount ofsample available.

In a representative experiment, an aliquot of an A-B-A triblockcopolymer which had been selectively sulfonated in the elastomeric Bblock, Polymer T-2 in Table 3, was dissolved in a mixture of THF/MeOHand the solution was cast onto a Teflon coated foil surface. Severalsamples of the membrane were prepared for tensile testing (Mini-D die).The “dry” samples gave tensile at break values of 4410 psi (average)strength with an elongation of 290%. Clearly these were strong, elasticfilms. Several of the test samples stamped from the same film wereequilibrated under water (for a day) prior to testing and the tensiletesting apparatus was employed in such a way that the samples could bepulled while fully submerged under water (data labeled “Wet” in Table4). On average, the wet samples had strength at break in tensile, underwater, of 1790 psi with elongation at break of 280%. Even in the wetstate, this membrane was strong and very elastic. Surprisingly, thistriblock copolymer which had been selectively sulfonated in the interiorsegment had retained, when fully hydrated, over 40% of the strength ofthe analogous polymer when tested in the dry state; the wet polymer hadessential the same elongation at break as had been observed when test inthe dry state. An elastomeric membrane having excellent wet strength andelongation properties was prepared by solvent casting a polymer of thepresent invention.

As shown in Table 4, sulfonated adducts of Polymers T-1, T-3, T-2.1, andTS-1, illustrative embodiments of the present invention, affordedmembranes with exceptional wet strength and elasticity.

In contrast to the surprising results obtained with the inventivepolymers as described above, films cast from the comparative examplepolymers, polymers sulfonated selectively in the end blocks (Aldrich 1)and polymers non-selectively sulfonated in all segments (sulfonatedadducts of Polymers A-1.1 and A-2), had poor wet tensile strengths. Inthe example employing the Aldrich 1 polymer, the wet test films were tooweak to give a detectable response in the tensile test. With theexceptions of experiments with Polymers A-1 and G-1, the films from thecomparative example polymers had lost nearly all (range from over 80 to100% loss of tensile strength) of their strength when tested in the wetstate by comparison to the properties measured on the samples testedwhen dry. Clearly films prepared from sulfonated block copolymers havingthese structures will be disadvantaged in applications where themembranes will get wet.

As will be shown later, the G-1 polymer and the A-1 polymer were notsufficiently sulfonated to have effective water transport properties.While these polymers demonstrated fair performance in the wet tensiletest, they were not sulfonated to a sufficient level to give effectivesemi permeable membranes.

An aliquot of an A-B-A block copolymer having only plastic blocks(poly-p-t-butylstyrene end segments and a polystyrene interior segment),which had been selectively sulfonated in the polystyrene interiorsegment, T-4, was dissolved in THF and the solution was cast onto aTeflon coated foil surface. Several samples of the resulting membranewere prepared for tensile testing (Mini-D die). The “dry” samples gave atensile strength at break value of 1800 psi (average) at an elongationof 14%. This was a very plastic material, which went through a yieldingevent with elongation and then failed. Several of the test samplesstamped from the same film were equilibrated under water (for a day)prior to testing and the tensile testing apparatus was employed in sucha way that the samples could be pulled while fully submerged under water(data labeled “Wet” in Table 4). On average, the wet samples hadstrength at break in tensile, under water, of 640 psi with elongation atbreak of 38%. In the wet state, this membrane was strong and moreflexible. Surprisingly, this triblock copolymer which had beenselectively sulfonated in the interior segment had retained, when fullyhydrated, over 30% of the strength of the analogous polymer when testedin the dry state; the wet polymer had a substantially improvedelongation at break by comparison to what had been observed when testedin the dry state. The flexibility of the polymer was enhanced as aconsequence of the water selectively plasticizing the sulfonatedpolystyrene phase. A firm, plastic membrane having good wet strength andimproved toughness when wet was prepared by solvent casting a polymer ofthe present invention. This polymer was prepared by selectivelysulfonating a plastic triblock copolymer in the interior segment.Membranes derived from casting a related, sulfonated polymer, T-5,afforded even better results in the wet tensile test (see Experiments91-57 and 91-74 in Table 4). As illustrated by membranes prepared fromTS-2, insertion of a short rubber segment between the sulfonationresistant p-t-BS end segments and the sulfonation susceptible S interiorsegment afforded sulfonated materials with even better wet mechanicalperformance. The mechanical properties of these materials in the drystate were also quite good (see Polymers TS-2 and TS-2.1 in Table 4).

As shown in Table 4, the results for a membrane cast from a selectivelysulfonated plastic triblock copolymer having poly-para-methylstyrene endsegments and a polystyrene center segment were even more striking. Inthe dry state, this polymer was so brittle that a test sample could notbe stamped from the “dry” as cast membrane; the specimen shattered inthe stamping operation. The film was then soaked in water for a day.Test specimens were easily stamped from the wet film once the sulfonatedpolystyrene block had been plasticized by the water. Under water tensiletesting found this polymer membrane to have good strength, 1800 psitensile strength at break, and strikingly improved toughness.

For the results on the related, membranes prepared from the selectivelysulfonated, plastic, A-B-A triblock copolymer having polyethylene endsegments and a polystyrene interior block, see the data in Table 4.

It is apparent from these data that, when used in a wet environment,membranes prepared from thermoplastic block copolymers of the presentinvention, which are selectively sulfonated in the B block will havegood strength, toughness, and flexibility properties. As it isenvisioned that many of the applications for products of the presentinvention will be in wet environments, these materials will besubstantially advantaged.

TABLE 4 Tensile Properties of Membranes Cast From Sulfonated BlockCopolymers. Tensile Tensile Polymer Strength (psi) Elongation (%) IDPolymer Type Wet Dry W/D Wet Dry W/D COMPARATIVE EXAMPLES Aldrich-1S-E/B-S 0 780 0 0 650 0 G-1 S-E/B-S 650 1200 0.54 370 630 0.59 A-1S-S/E/B-S 770 3770 0.20 540 830 0.65 A-1.1 S-S/E/B-S 460 3440 0.13 410580 0.71 A-2 S-S/E/B-S 230 2950 0.08 140 230 0.61 A-2 S-S/E/B-S 90 31500.03 60 310 0.19 A-3 S-S/E/B-S 1700 3360 0.51 300 230 1.3 INVENTIVEEXAMPLES T-1 (ptBS-S/E/B)_(n) 2366 3682 0.64 121 142 0.85 T-2(ptBS-S/E/B)_(n) 1790 4410 0.41 280 290 0.97 T-2.1 (ptBS-S/E/B)_(n) 33003300 1.0 280 180 1.6 T-2.1 (ptBS-S/E/B)_(n) 2430 3360 0.72 300 290 1.0T-2.1 (ptBS-S/E/B)_(n) 2050 3850 0.53 140 220 0.66 T-2.1(ptBS-S/E/B)_(n) 2270 4630 0.49 160 190 0.84 T-3 (ptBS/S-S/E/B)_(n) 27703660 0.76 310 260 1.19 T-4 (ptBS-S)_(n) 643 1799 0.36 38 14 2.71 T-5(ptBS-S)_(n) 1480 Brit Inf 66 Brit Inf T-5 (ptBS-S)_(n) 870 Brit Inf 66Brit Inf T-5 (ptBS-S)_(n) NA TS-1 (ptBS-E/B-S)_(n) 2940 3194 0.92 510390 1.3 TS-1.1 (ptBS-E/B-S)_(n) 1110 1440 0.77 180 28 6.4 TS-2(ptBS-E/B-S)_(n) 1600 2130 0.75 150 7 21 TS-2.1 (ptBS-E/B-S)_(n) 47405870 0.81 5 16 3.2 P-1 (pMS-S)_(n) 1827 Brit Inf 5 Brit Inf E-1(PE-S)_(n) 111 NA NA 6 NA NA Where S = styrene, E = ethylene, B =butylene, ptBS = para-tert-butylstyrene, E/B is hydrogenatedpolybutadiene, and PE = hydrogenated low vinyl content polybutadiene,“Aldrich-1” was used as purchased from Aldrich Chemical Company (Productnumber 44885), “Brittle” or “Brit” denotes a membrane that shatteredwhen an attempt was made to stamp a tensile test specimen from the film,“Infinite” or “Inf” was reserved for the value of the ratio of wet todry properties when the dry membrane was too brittle to test. NA = notanalyzed

Illustrative Embodiment #5

In Illustrative Embodiment #5, the sulfonated polymers were tested byDynamic Mechanical Analysis. Dynamic mechanical analysis was performedon both sulfonated and precursor polymers using a DMA 2900 manufacturedby TA Instruments. Scans were performed using 10 Hz oscillation and a 2°C./min temperature ramp on solvent cast film samples. The temperaturerange tested was from −100° C. to 200° C. for the sulfonated polymers to−100° C. to 120° C. for the precursor polymers. FIG. 1 shows acomparison of the storage modulus of sample T-3 before and aftersulfonation. This figure shows that the midpoint of the glass to rubbertransition, Tg, of the S/EB interior block moves from approximately 15°C. to approximately 50° C. Similarly, FIG. 2 shows a similar increase inthe Tg of the interior block of sample T-2. These increases demonstratethat in both samples the interior block is sulfonated to a degree thatresults in a significant change in the physical properties of thesample.

Illustrative Embodiment #6

Swelling studies on polymeric materials have been taken as a measure ofdimensional stability (or lack thereof) for articles prepared from aparticular polymer in the presence of a specific swelling agent. In thepresent case, swelling studies in water were carried out on the solutioncast films of the sulfonated block copolymers described in Table 4. Inthe extreme, it would be desirable to have polymers sulfonated at veryhigh levels (for good water transport performance) that affordedmembranes with excellent dimensional stability (very little swelling) inthe presence of water.

In an example of the present invention, a “dry” as cast film preparedfrom the selectively sulfonated adduct of an elastomeric A-B-A triblockcopolymer having poly-p-t-butylstyrene end segments and an elastomericinterior block being a hydrogenated copolymer of butadiene and styrenewas weighed (Polymer T-2), submerged in a pan of water for a day,removed from the water, blotted dry, and reweighed. From thisexperiment, it was discovered that the film had a 62% increase in weightas a result of being immersed in water for a day. Samples taken atshorter amounts of time demonstrated the film had reached an equilibriumweight gain in less than a few hours. The weight gain after 1 day underwater was taken as a measure of the equilibrium swelling for this film.As shown in Table 5, the equilibrium swelling results are typicallylower for films cast from the other selectively sulfonated in theinterior segment copolymers, for both elastomeric and plastic precursorpolymers. They would be expected to demonstrate even better dimensionalstability when used in wet applications.

By comparison, the results of similar experiments conducted on filmscast from the comparative example polymers which had been sulfonatedeither in the end blocks or indiscriminately in all parts of the blockcopolymer were inferior. In these systems, swelling could only becontrolled by reducing the level of functionality of the polymer. Atuseful levels of sulfonation, swelling levels as high as 280% wereobserved; these films have very poor dimensional stability by comparisonto polymers of the present invention. A lower level of swelling wasrealized in Comparative Example Experiments with Polymers A-1 and G-1having lower levels of sulfonation. But, as will be shown later, thereduced level of swelling came at the cost of essentially no watertransport performance. In the comparative example polymers, it was notpossible to have a membrane that had both effective water transportproperties and good dimensional stability (as measured by swellingexperiments) in a wet environment. Block copolymers of the presentinvention which are selectively sulfonated in the center block werefound to afford films that were advantaged in dimensional stability inwet environments.

TABLE 5 Water Uptake for Membranes Cast From Sulfonated Polymers.Sulfonation Level —SO₃H/polymer Equilibrium Swell Polymer ID PolymerType (mmol/g) (% wt gain) COMPARATIVE EXAMPLES Aldrich 1 S-E/B-S 1.3-1.6180 G-1 S-E/B-S 0.9 11 A-1 S-S/E/B-S 0.6 8 A-1.1 S-S/E/B-S 1.1 110 A-2S-S/E/B-S 1.6 88 A-2 S-S/E/B-S 1.9 280 A-3 S-S/E/B-S 1.6 (avg) 56INVENTIVE EXAMPLES T-1 (ptBS-S/E/B)_(n) 1.0 30 T-2 (ptBS-S/E/B)_(n) 1.362 T-2.1 (ptBS-S/E/B)_(n) 1.5 27 T-2.1 (ptBS-S/E/B)_(n) 1.0 63 T-2.1(ptBS-S/E/B)_(n) 1.5 9.0 T-2.1 (ptBS-S/E/B)_(n) 1.4 24 T-3(ptBS/S-S/E/B)_(n) 1.2 35 T-4 (ptBS-S)_(n) 2.8 74 T-5 (ptBS-S)_(n) 1.841 T-5 (ptBS-S)_(n) 3.2 96 T-5 (ptBS-S)_(n) NA 15 TS-1 (ptBS-E/B-S)_(n)1.5 19 TS-1.1 (ptBS-E/B-S)_(n) 1.8 NA TS-2 (ptBS-E/B-S)_(n) 2.5 15TS-2.1 (ptBS-E/B-S)_(n) 1.8 NA P-1 (Pms-S)_(n) 2.2 25 E-1 (PE-S)_(n) NA34

See footnote to Table 4 for an explanation of the symbols andabbreviations used in this table.

Illustrative Embodiment #7

The solvent cast films described in Illustrative Embodiment #4 and therelated Comparative Example materials described in Table 4 were testedto determine the rate at which water passed from one side of themembrane to the other. The water vapor transmission (WVT) rate wasmeasured on films about 1 mil thick using the ASTM E96-00 “desiccant”method. In this test a small, open topped vessel containing anactivated, dry desiccant was covered with the membrane to be tested. Themembrane was sealed to the top of the vessel and this assembly wasweighed. The testing device was exposed to the atmosphere in acontrolled temperature (75° F. (23.9° C.)) and controlled humidity(relative humidity 50%) for a week and reweighed to see how much waterhad passed through the membrane and been absorbed by the desiccant.Knowing the time of the test, the thickness and exposed surface area ofthe membrane, and the weight of the water absorbed, the WVT rate can becalculated and has been reported as Permeability (g of H2O/Pa.m.h.).

The membrane prepared from the inventive polymer, selectively sulfonatedT-2, was found to have a water permeability of 1.2×10-6 g/Pa.m.h., aneffective transmission rate. In addition, this membrane had excellentwet strength and elongation properties. The polymer used in making thismembrane was prepared by selectively sulfonating an elastomeric triblockcopolymer in the interior segment. As shown in Table 6, membranesprepared from the other selectively sulfonated, elastomeric, A-B-Apolymers of the present invention, Polymers T-1 and T-3, also hadeffective WVT rates and were superior to the comparative polymermembranes in wet strength and dimensional stability.

The membrane prepared from the inventive polymer, selectively sulfonatedT-4, was found to have a water permeability of 9.0×10-6 g/Pa.m.h., aneffective transmission rate. This WVT rate exceeds (by a factor of about3) that of any other polymer in Table 6. In addition, this membrane hadgood wet strength, demonstrated good toughness and flexibility, and hadgood dimensional stability in the presence of water. The polymer used inmaking this membrane was prepared by selectively sulfonating athermoplastic triblock copolymer in the interior segment. As shown inTable 6, membranes prepared from the other selectively sulfonated,thermoplastic, A-B-A polymers of the present invention, Polymers P-1 andE-1, also had exceptional WVT rates and superior wet strength anddimensional stability in a wet environment. This property set offers asignificant advance in the performance of membranes that are capable oftransporting water.

As expected, several of the membranes prepared from sulfonated adductsof the comparative example polymers had effective water transmissionrates with values ranging from 3.6×10-7 to 2.6×10-6 g/Pa.m.h. Themembrane prepared from the sulfonated polymer A-1 sulfonated inExperiment 45-28 was the notable exception; there was essentially noflow of water through this membrane at all, permeability=2.3×10-9g/Pa.m.h. The glaring problem with these membranes (Experiment 45-28)made from polymer A-1 was that they had little or no wet strength andhad poor dimensional stability in the presence of water. They will bevery difficult to use in applications that involve a wet environment.The membranes prepared according the current invention will have goodwater transport rates and will have robust mechanical properties in thepresence of water.

TABLE 6 Water Vapor Transmission Rates for Membranes Solvent Cast FromSulfonated Triblock Copolymer Solutions. Wet Equilibrium TensilePermeability Polymer Polymer swelling Strength (10⁻⁶ g/ ID Type (% wtgain) (psi) Pa · m · h) COMPARATIVE EXAMPLES Aldrich-1 S-E/B-S 180 0 3G-1 S-E/B-S 11 650 0.078 A-1 S-S/E/B-S 8 770 0.0023 A-1.1 S-S/E/B-S 110460 1.5 A-2 S-S/E/B-S 90 230 0.99 A-2 S-S/E/B-S 280 90 2.6 INVENTIVEEXAMPLES T-1 (ptBS- 30 2370 1.7 S/E/B)_(n) T-2 (ptBS- 62 1790 1.2S/E/B)_(n) T-3 (ptBS/S- 35 2770 0.30 S/E/B)_(n) T-4 (ptBS-S)_(n) 74 6409.0 P-1 (pMS-S)_(n) 25 1830 NA E-1 (PE-S)_(n) 34 11 NA

See footnote to Table 4 for an explanation of the symbols andabbreviations used in this table.

Illustrative Embodiment #8 Preparation of a Selectively Sulfonated(A-B-D)x Block Copolymer (Hypothetical)

A living triblock copolymer arm, ptBS-S-Bd-Li, would be prepared usingliving anionic polymerization methods with sequential addition of themonomers. The living triblock copolymer arm would be coupled affording amixture of linear and branched polymer chains having sulfonationresistant end segments of poly-para-tert-butylstyrene (ptBS),sulfonation susceptible inner segments of polystyrene (S) and theprecursor for an impact modifying, sulfonation resistant block ofhydrogenated polybutadiene (E/B) in the center of the molecule.

In a representative experiment, the polymerization of 26 g ofpara-tert-butylstyrene monomer in a mixture containing 940 g ofcyclohexane and 60 g of dry diethyl ether would be initiated, underanionic polymerization conditions, at 40 C, by the addition of 1 mmol ofsec-BuLi. Upon complete conversion of the monomer, an analytical sampleof the living poly-para-tert-butylstyrene would be terminated by theaddition of an excess of MeOH and the terminated product analyzed by aGPC method to find a polymer having a true MW=26,000 g/mol. Having madethe first block of the polymer arm, 52 g of styrene monomer would beadded to the living polymer solution. Upon complete conversion of themonomer, an analytical sample of the livingpoly-para-t-butylstyrene-polystyrene diblock copolymer would beterminated by the addition of an excess of MeOH and the terminatedproduct analyzed by a GPC method to find a polymer having a trueMW=78,000 g/mol. This would correspond to a ptBS-S diblock copolymerhaving segment molecular weights of 26,000-52,000 respectively. Havingmade the second block of the copolymer arm, 20 g of 1,3-butadienemonomer would be added to the living polymer solution. Upon completeconversion of the monomer, an analytical sample of the livingpoly-para-t-butylstyrene-polystyrene-polybutadiene triblock copolymerwould be terminated by the addition of an excess of MeOH and theterminated product analyzed by a GPC method to find a polymer having atrue MW=98,000 g/mol. This would correspond to a ptBS-S-Bd blockcopolymer having segment molecular weights of 26,000-56,000-20,000respectively. Analysis of the triblock copolymer using H-NMR would beexpected to find about 40% of the butadiene to have added by a1,2-addition mechanism. Having made the third block of the copolymerarm, the living polymer arms would be coupled by the addition of 0.04mmol of tetramethoxysilane (TMOS) (Si/Li=0.4/1(mol/mol)). Analysis ofthe coupled polymer solution using a GPC method would be expected tofind a mixture of branched (major component) and linear coupledpolymers, (ptBS-S-Bd)TMOS with less than 10% of the arms remaining asunlinked triblock copolymer chains.

The cyclohexane/diethyl ether solution of the freshly polymerized(ptBS-S-Bd)TMOS mixture would be transferred to a pressure vessel.Hydrogen would be added to a pressure of 700 psig. A suspension (in anamount equivalent of 0.2 g of Co) containing the reaction productderived from the addition of Co(neodecanoate)2 and triethylaluminum(Al/Co=2.6/1 (mol/mol) would be added to the reactor to initiatehydrogenation. When the hydrogenation reaction is complete (99% of theC═C centers were hydrogenated as measured using a H-NMR technique),excess hydrogen gas would be vented off and the selectively hydrogenatedpolymer, (ptBS-S-E/B)TMOS, would be contacted with an excess of 10% wtsulfuric acid in water and exposed to the air (Care would be taken inthis step to avoid the formation of an explosive mixture of hydrocarbonand air.). Contacting the polymer cement with air in the presence of anexcess of acid will result in the oxidation of the hydrogenationcatalyst and extraction of the inorganic catalyst residues into theaqueous phase. The polymer solution would be washed with water to removeany acid species that might be in the organic phase. About 100 g of theselectively hydrogenated polymer would be recovered by coagulation withMeOH, collection by filtration, and dried. An aliquot of this polymerwould be analyzed by DSC and the Tg of the impact modifier phase wouldbe found to be below 0° C.

An aliquot of the new polymer, (ptBS-S-E/B)TMOS would be selectivelysulfonated in the center segment using the procedure outlined inExperiment 43-51 used for T-4. A 20 g portion of the new polymer havinga sulfonation resistant, impact modifying, center block would bedissolved in 1,2-dichloroethane (DCE) (500 g) and the solution heated to49 C. The acetyl sulfate reagent would be prepared in a separate vesselby combining a cold (ice bath) solution of acetic anhydride (AcOAc) (18g, 0.18 mol) in DCE (20-30 ml) with cold sulfuric acid (10.4 g, 0.11mol). The cold solution of acetylsulfate would be added with stiffing tothe polymer in DCE solution. Sulfonation conditions would be maintainedfor 4.1 hr. The multiblock copolymer, which would have been selectivelysulfonated in the inner styrene segments, would be isolated bycoagulation in an excess of water, washed with water to remove acidicresidues which were not bound to the polymer (until the wash water wasneutral in pH), and dried under vacuum. An aliquot of the dry,selectively sulfonated polymer (1.04 g) would be dissolved in a mixtureof toluene and methanol (MeOH) (1/2 (v/v)) and the polymer boundsulfonic acid functionality would be titrated to a thymol blue endpointusing a solution of sodium hydroxide (NaOH) (0.14 N) in methanol/water(80/20 (w/w)). This analysis would be expected to find that about 37 mol% of the polystyrene sites in the interior block of the copolymer hadbeen sulfonated.

An aliquot of the selectively sulfonated A-B-D-B-A block copolymerhaving sulfonation resistant end blocks (poly-p-t-butylstyrene endsegments) and impact modifying center block (hydrogenated polybutadiene)and having sulfonation susceptible polystyrene inner segments would bedissolved in a THF/MeOH (3/1(v/v)) solvent mixture and the solutionwould be cast onto a Teflon coated foil surface. Several samples of theresulting membrane would be prepared for tensile testing (Mini-D die).The “dry” samples would be expected to give tensile strength at breakvalues in excess of 1800 psi (average) at an elongation of more than14%. This would be a very flexible material. Several of the test samplesstamped from the same film would be equilibrated under water (for a day)prior to testing and the tensile testing apparatus would be employed insuch a way that the samples could be pulled while fully submerged underwater. On average, the wet samples would be expected to have strength atbreak in tensile, under water, in excess of 500 psi with elongation atbreak in excess of 38%. In the wet state, this membrane would be strongand flexible. Surprisingly, this triblock copolymer which had beenselectively sulfonated in the inner styrene segments would be expectedto have retained, when fully hydrated, over 30% of the strength of theanalogous polymer when tested in the dry state. The flexibility of thepolymer would have been enhanced as a consequence of the waterselectively plasticizing the sulfonated polystyrene phase. A firm,flexible, membrane having good wet strength and improved toughness whenwet would have been prepared by solvent casting a polymer of the presentinvention. This polymer would have been prepared by selectivelysulfonating a polymer having an impact modifying block in the center(interior) of the molecule.

Swelling studies on the new, selectively sulfonated polymer, conductedaccording the process outlined in Illustrative Embodiment #6, would beexpected to find the selectively sulfonated (ptBS-S-E/B)TMOS polymer totake up less than 100% of its weight in water at equilibrium. From thisresult, it would be concluded that materials prepared from this polymerwould have good dimensional stability in the presence of water.

Using the procedure outlined in Illustrative Embodiment #7, membranesprepared from the selectively sulfonated (ptBS-S-E/B)TMOS polymer wouldhave been tested for water transport rates. This test would be expectedto find these polymers to have water permeability values in excess of0.1×10-6 g/Pa.m.h . From this result, it would be concluded that thesemembranes are very effective for the transport of water.

These experiments would be expected to show that the selectivelysulfonated polymer having sulfonation resistant outer blocks,sulfonation susceptible inner segments, and a sulfonation resistant,impact modifying block in the center of the molecule would affordarticles having good dimensional stability in the presence of water,useful levels of strength, excellent toughness and flexibility, andeffective water transport properties.

Illustrative Embodiment #9 Control of Mechanical Performance and Stateof Water Via Casting Conditions

In this example an aliquot of the sulfonated block copolymer TS-1 basedon (A-D-B)nX which had been selectively sulfonated in the B block wascast from three different solvent mixtures (Table 7), in air, at roomtemperature, onto the surface of Teflon coated foil. The resulting filmswere tested as cast (data labeled “Dry”). Test specimens were tested forwater uptake, water permeation, state of water in the film, and tensilestrength in both the wet and dry state. Water swelling studies wereperformed as described in Illustrative Embodiment #6, and wet and drytensile measurements were performed as described in IllustrativeEmbodiment #4. Atomic force microscopy was performed to view themorphology of the three membranes. The state of water was measured usingthe differential scanning calorimetry (DSC) method set forth in thepublications by Hickner and coworkers titled “State of Water inDisulfonated Poly(arylene ether sulfone) Copolymers and aPerfluorosulfonic Acid Copolymer (Nafion) and Its Effect on Physical andElectrochemical Properties”, Macromolecules 2003, Volume 36, Number 17,6281-6285 and “Transport in sulfonated poly(phenylene)s: Protonconductivity, permeability, and the state of water”, Polymer, Volume 47,Issue 11, Pages 4238-4244. Water permeation rate measurements weremeasured by the method set forth in the publication by N. S. Schneiderand D. Rivin “Solvent transport in hydrocarbon and perfluorocarbonIonomers”, Polymer, Volume 47, Issue 9, Pages 3119-3131.

TABLE 7 Effect of casting conditions on Membrane properties. Water DryWet Water Perm rate Water heat of Solvent Tensile Tensile Uptakeg-mil/day- fusion (ΔH_(f)) mixture (PSI) (PSI) (wt %) m² (J/g) 90/103100 2600 18 2700 191 Toluene/MeOH 80/20 3800 2700 21 3500 257THF/Toluene 50/50 4300 2300 21 1160 65 THF/Toluene

Atomic force microscopy (FIG. 3) shows that different structures wereformed from the three different casting solutions. While all three filmshave exceptional wet and dry strength, the strength of each filmdiffered (Table 7). Each film also had similar water uptake of 18 to 21wt % (Table 7).

It is surprising that each film has a different mechanism of storingwater as measured by DSC (FIG. 4). FIG. 4 shows two overlappingendothermic peaks for each sample, which consist of the broad meltingpeak range from −30° C. to 10° C., assigned to the weakly bound waterand the sharp melting peak at 0° C. due to the free water. The amount ofbound and free water is indicated by the location and broadness of themelting peaks and variations in ΔHf (Table 7). Low values of ΔHfindicate tightly bound water (ΔHf for bulk water is 334 J/g), as thetightly bound water is not able to freeze. Varying the relative amountsof bound versus free water allows for the tuning of transport propertieswith a single sulfonated polymer. In this example the water permeationrate is increased by more than a factor of three via changes in theamount of bound water.

Illustrative Embodiment #10

In Illustrative Embodiment #10, the sulfonated polymers were tested formechanical stability in boiling water. A piece of sulfonated polymermembrane approximately 0.75″ wide by 3″ long was suspended in acontainer of boiling water. The lower end of the film was weighed downwith a 3 g binder clip to prevent the sulfonated membrane from floatingin the water. After boiling the membrane for 15 minutes, the sampleswere removed and measured for changes in dimension. The results areshown in Table 8. Both the 0091-49 and 0091-67A-3 and G-2 samples(comparative examples) gave undesirable results. The samples swelled tosuch a large extent that they began to tear at the clips during thetesting and tore upon removal from the clips after testing.Surprisingly, the 0091-85 and 0091-91TS-1 and TS-2 samples (samples ofthe present invention) did not swell noticeably and retained theiroriginal dimensions following the testing. This is feature is highlydesirable in applications such as methanol fuel cells as a clampedmembrane would potentially be cycled through wet and dry atmospheres anddimensional stability is paramount.

TABLE 8 Swelling and membrane stability in boiling water. SwellingPolymer (% increase Polymer type ID in size) Observation S-S/E/B-S A-3180 Sample broke upon extraction from water S-E/B-S G-2 175 Sampletearing at clips due to swelling and tore upon removal from clamps(ptBS-E/B-S)n TS-1 <10 Slight shrinkage after drying (ptBS-E/B-S)n TS-2<10 Slight embrittlement after drying

1. A method of varying the transport properties of a film cast of asulfonated block copolymer that are solids in water comprising at leasttwo polymer end blocks A and at least one polymer interior block Bwherein: a. each A block is a polymer block resistant to sulfonation andeach B block is a polymer block susceptible to sulfonation, said A and Bblocks containing no significant levels of olefinic unsaturation; b.each A block independently having a number average molecular weightbetween 1,000 and 60,000 and each B block independently having a numberaverage molecular weight between 10,000 and 300,000; c. each A blockcomprising at least one segment of one or more polymerizedpara-substituted styrene monomers and optionally one or more segmentsselected from polymerized (i) ethylene, (ii) alpha olefins of 3 to 18carbon atoms; (iii) 1,3-cyclodiene monomers, (iv) monomers of conjugateddienes having a vinyl content less than 35 mol percent prior tohydrogenation, (v) acrylic esters, (vi) methacrylic esters, and (viii)mixtures thereof, wherein any segments containing polymerized1,3-cyclodiene or polymerized conjugated dienes are subsequentlyhydrogenated and wherein any A block comprising polymerized ethylene orhydrogenated polymers of a conjugated, acyclic diene have a meltingpoint greater than 50° C.; d. each B block comprising segments of one ormore vinyl aromatic monomers selected from polymerized (i) unsubstitutedstyrene monomers, (ii) ortho-substituted styrene monomers, (iii)meta-substituted styrene monomers, (iv) alpha-methylstyrene, (v)1,1-diphenylethylene, (vi) 1,2-diphenylethylene and (vii) mixturesthereof; e. said B blocks are sulfonated to the extent of 10 to 100 molpercent, based on the units of vinyl aromatic monomer in said B blocks;and f. the mol percent of vinyl aromatic monomers which areunsubstituted styrene monomers, ortho-substituted styrene monomers,meta-substituted styrene monomers, alpha-methylstyrene,1,1-diphenylethylene and 1,2-diphenylethylene in each B block beingbetween 10 mol percent and 100 mol percent; and g. said sulfonated blockcopolymer is non-dispersible and solid in water, and has a tensilestrength greater than 100 psi in the presence of water according to ASTMD412 after immersion in water for 24 hours; said method comprisingcasting said polymer using a solvent mixture comprising two or moresolvents selected from the group consisting of polar solvents andnon-polar solvents and mixtures thereof.
 2. The method of claim 1,wherein the polar solvents are selected from alcohols having from 1 to20 carbon atoms; ethers having from 1 to 20 carbon atoms; esters ofcarboxylic acids, esters of sulfuric acid, amides, carboxylic acids,anhydrides, nitriles and ketones having from 1 to 20 carbon atoms. 3.The method of claim 2, wherein the polar solvents are selected frommethanol, ethanol, propanol, isopropanol, dimethyl ether, diethyl ether,dipropyl ether, dibutyl ether, substituted and unsubstituted furans,oxetane, dimethyl ketone, diethyl ketone, methyl ethyl ketone,substituted and unsubstituted tetrahydrofuran, methyl acetate, ethylacetate, propyl acetate, methyl sulfate, dimethyl sulfate, carbondisulfide, formic acid, acetic acid, acetone, cresol, creosol,dimethylsulfoxide (DMSO), cyclohexanone, dimethyl acetamide, dimethylformamide, acetonitrile, water and dioxane.
 4. The method of claim 3,wherein the non-polar solvents are selected from toluene, benzene,xylene, mesitylene, hexanes, heptanes, octanes, cyclohexane, chloroform,dichloroethane, dichloromethane, carbon tetrachloride, triethyl-benzene,methylcyclohexane, isopentane and cyclopentane.